Momentum 1, Momentum, Momentum, Momentum, Physical Science Chapter 12, physics 9 FINAL, Unit 1 Physics review, Momentum
a car brakes suddenly and the velocity changes from 25 m/s to 0 in 5 seconds. what is its acceleration?
-5m/s
a roller coaster traveling at 4 m/s speeds up to 14 m/s in 2 seconds as it goes down a hill. what is the acceleration
5 m/s
a person rides a bike with a constant velocity if 2 m/s. if his total displacement is 10 m, for how long was he riding
5 seconds
6.0 mega grams is equivalent to
6,000 kilograms
What is the momentum of a 5 kg object that has a velocity of 1.2 m/s?
6.0 kg m/s
What is the momentum of a 5 kg object that has a velocity of 1.2 m/s?
6.0 kg • m/s
A cannon recoils from launching a cannonball, the speed of the cannon's recoil is small because
Cannon has far more mass than cannonball
Impulse
Change in momentum
on the way to a concert, john stops at the mall to buy some camera film. if you divide the distance he travels to the concert by his average speed for the entire trip, you are calculating what
time interval
The inertia of two objects Must be the same if the product of their mass and velocity are the same.
true
Give an example of an Elastic collision.
two pod balls collide and bounce off eachother. No loss of energy
A boat travels 4,000 meters in 20 minutes. What is the boat's average velocity?
v=200 meters/ min
What two parts does a measurement have?
value and unit
what two parts does a measurement have?
value and unit
the slope of a position versus time graph represents
velocity
when you throw a ball up in the air, it travels up and then stops instantaneously before falling back down. at the point where it stops and changes direction to fall back down its:
velocity is zero
calculate the work done to lift the barbell weighing 200 N a distance of 1.25 meters
w=250J
Collision
when two objects hit
Anya knows the velocity of an object. What else does she need to know in order to find the object's momentum
It's mass
Denise is riding her bike and falls to the ground. During the collision, she hits both grass and cement.
The grass extends the time of the collision
Denise is riding her bike and falls to the ground. During the collision, she hits both grass and cement.
The grass extends the time of the collision.
If 2 objects have the same momentum, then
The heavier object will travel slower
A cannonball is launched from a cannon. The IMPULSE on the cannon compared to the cannonball is
The same
If you crash into a wall or driver into an identical car driving at the same speed, what would cause more damage
The same amount of damage would occur
When a car comes to a full stop after hitting a brick wall and hitting a water filled barrel, the change in momentum is: greater hitting the wall, greater hitting the barrel, the same momentum change in both.
The same momentum change in both.
What has more momentum, a car traveling at 30 m/s or the same car traveling at 60 m/s?
The second one because it's going faster
Accuracy
The state of being correct
weight is the force of gravity on an object
True
Often, the forces on an object are unbalanced. An unbalanced force is a force that results when the net force acting on an object is not equal to zero. When an unbalanced force acts on an object, the object accelerates
Unbalanced Forces
Which had more momentum, a worm crawling across the road or a car parked on the road?
Worm
The chart shows masses and velocities of four objects. Which lists the objects in order, from least to greatest momentum?
Y, W, X, Z
When you ride a bike at full speed, which has a greater momentum, you or the bike?
You
If you increase time
You decrease force Vice versa Ft=m*change v
The chart lists the masses and velocities of four objects. Which object requires the greatest change in momentum in order to stop its motion?
Z
when two objects hit each other what occurs?
a collision
Force
a push or pull
A car suddenly stops going from 25 m/s to 0 m/s in 4 seconds. What is its acceleration?
a= -6.25 m/s2
A roller coaster traveling at 8 m/s speeds up to 12 m/s in 3 seconds as it goes down a hill. What is the acceleration?
a= 1.3 m/s2
Glen rolls down a hill on his bike. He was going 12 mph at first, then was going 18 mph at the bottom 4 seconds later. What was his acceleration?
a= 1.5 mph/sec
the rate of change in the speed of an object is known as
acceleration
the slope of a velocity versus time graph represents
acceleration
Even though every action has an equal and opposite reaction force, they do not cancel one another and motion may still occur because the
action and reaction forces are applied to different objects
Why do action/reaction forces NOT cancel each other out?
action and reaction forces are applied to different objects
According to Newton's third law of motion, which are equal?
action force and reaction force
in order to be scientific, evidence must be
both relatable and objective
In order to be considered scientific, evidence must be what two things?
both repeatable and objective
if you know the distance to traveled and the amount of time it took, speed may be calculated by
dividing distance by time
the slope of the line of a graph is calculated by
dividing the change in the vertical values by the change in the horizontal values
is two billiards colliding and bouncing off eachother inelastic or elastic?
elastic
the ability to cause change is defined as
energy and is measured in joules
a carefully designed test done under controlled conditions
experiment
what net force is requiered to accelerate a 10 kg wagon by 4 m/s2
f=40n
why are SI units used so often in science?
factors of 10 are easier to work with mathematically
what is NOT a metric measurement
foot
What is an example of an English measurement that is NOT used in the Metric system?
foot, inch, quart, gallon, etc.
a push, pull, or other action that has the ability to change motion is called a
force
Newton's Second Law of Motion
force is mass times distance
the newton is defined as the
force that can give a 1kg mass an acceleration of 1 m/s^2
Work
force times distance
in science work is defined as
force x the distance moved in the same direction as the force
the equation that correctly expresses newtons second law
force=mass*acceleration (f=ma)
When an object is accelerating due to the force of gravity with no other forces acting on it, it is in___________
free fall
air bags reduce injury in automobile accidents by
increasing time of collision
the variable usually represented on the x-axis of a graph is the ~what~ variable?
independent
newtons first law is also known as the law of
inertia
When someone throws a ball, the action force is the person pushing on the ball. What is the reaction force?
the ball pushing on the person
More momentum equals
More mass or more velocity or both
the impulse necessary to change the momentum of a 20 kg object by 5 kg*m/s is
5 kg*m/s
the si unit of force preferred by scientists is the
newton
is colliding bodies sticking to one another an inelastic collision
no
Acceleration of an object MUST be caused by a force that is ___________ than zero.
not
You raise one penny per meter walked in a fundraiser. You walk 11 km. How many dollars do you raise?
$110
you raise a penny per meter walked by you in a fundraiser. you walk 15 km. how much money do you raise?
$150.00
The diagram shows two balls before they collide. What is the momentum of the system after the collision?
0.2 kg m/s
The diagram shows two balls before they collide. What is the momentum of the system after the collision?
0.2 kg • m/s
Gwennen rides her bicycle 2.4 kilometers up a steep hill in 8 minutes her speed is how many km/min
0.3 km
the amount if mechanical kinetic energy possessed by a 0.25-kilogram ball rolling at a speed of 2.5 meter per second is ______ joules
0.78
lifting a 70-kilogram barbell 2.0 meter above the floor increases its potential energy bu about
1,400 joules
The chart show the masses and velocities of two colliding objects that stick together after a collision. According to the law of conservation of momentum, the momentum of the object after the collision is ____ kg • m/s.
1,500
a boat travels 6,000 m in 40 minutes. whats the boats average velocity
2.5 m/s
jonah is pushing his younger sister on a swing. if she weighs 35 kg, how much higher above the ground must Jonah push her to increase her potential energy by 525 Joules
1.5 meters
you push a box with a force of 30 N on a frictionless horizontal floor snd the box accelerates at 2.5 m/s^2. what is its mass
12 kg
a digital timer displays a reading or 3:23:47. in seconds, this display represents how many seconds
12,227
ken rolls a 7k bowling ball so slowly that it stops before it moves through all of the pins. the impulse necessary to stop this bowling ball rolling at 2 m/s is how many newton-seconds
14
an object is dropped from rest and falls downward for 3 seconds. what is its average speed
14.7 m/s
calculate the work done to lift a barbell weighing 100 newtons a distance of 1.5 meters
150 joules
Doug rides a motorcycle at an average speed of 42 mph for 3.6 hours. The distance he travels is about how many miles?
150 miles
A bungee jumper falls off a tower and it takes 2 seconds for her bungee cord to pull her back up. What was her velocity in free fall after 2 seconds?(gravity * time)
19.26 m/s
a professional golfer walks at an average rate of 3.20 feet per second on the gold course. the amount of time required for her to walk from the tee to a green 612 feet away is
191 seconds
Recoil
2 objects start together and then move apart
what net force is required to accelerate a 10 kg wagon by 2 m/s^2
20 N
it takes a runner 2 seconds to accelerate to a speed of 5 m/s near the finish line of a race. if his acceleration is 1 m/s^2, what was his initial velocity
3 m/s
toby glances at the speedometer on his bike as he begins to roll downhill. it indicates he is traveling at 12 mph when he initially looks at it and 20 miles per hour 4 seconds later. what is his acceleration?
3 mph/s
A person rides a bike with a constant velocity of 2.5 m/s. If his total displacement was 8 meters, for how long was he riding?
3.2 Minutes
what is the acceleration of a 1,200kg car when a force of 4,200 N is applied?
3.5m/s^2
what impulse must be applied to a 3-kilogram object starting at rest to give is 150 joules of kinetic energy?
30 newton-seconds
the speed of a cheetah running 300 yards in 10s is
30 yards per second
the statement 300 kg per cubic meter represents
300 kg for each cubic meter, 300 kg for every cubic meter, and 300 kg divided by one cubic meter
"forces occur in pairs" is another way of stating Newtons:
3rd law of motion
Two carts collide and bounce apart. Cart 1 had a momentum of -6 kg • m/s before the collision. Cart 2 had a momentum of 10 kg • m/s before the collision. What is the total momentum of the carts after the collision?
4 kg m/s
Two carts collide and bounce apart. Cart 1 had a momentum of -6 kg • m/s before the collision. Cart 2 had a momentum of 10 kg • m/s before the collision. What is the total momentum of the carts after the collision?
4 kg • m/s
A car has a momentum of 20,000 kg • m/s. What would the car's momentum be if its velocity doubles?
40,000 kg m/s
A car has a momentum of 20,000 kg • m/s. What would the car's momentum be if its velocity doubles?
40,000 kg • m/s
the momentum of a 2,000 kg car traveling at 20 m/s is
40,000 kg*m/s
a ball is dropped off the roof of a tall building. if the ball reaches the ground in 3 seconds. what is the average speed?
44.1 meters
if a 40,000 kg rocket were traveling from its launch pad at a speed of 150 meters per seconds, 800 kilograms of gases would be expelled from the rocket at a speed of about:
7,500 m/s
shawna, who weighs 54 kg, is rollerblading on a level surface. if she is rolling at 12 m/s, to what height would she roll up an incline before stopping
7.3 meters
Shane rides a motorcycle at an average speed of 35 mph for 2.4 hours. What is the distance he travels
84 Miles
A bicycle has a momentum of 36 kg • m/s and a velocity of 4 m/s. What is the mass of the bicycle?
9 kg
a skydiver reaches an instantaneous velocity of 88.2 meters per second before opening his parachute. How long was he in free fall?
9 seconds
a bungee jumper falls off a tower and travels 2 seconds before the bungee cord starts to slow her down. what was her average velocity in free fall?
9.8m/s
the acceleration due to gravity is
9.8m/s^2 on earth, signified by the letter g, and a downward acceleration
a 60 kg person travels to the moon where the value of gravity is 1.6N/kg. what is the persons weight?
96 N
Acceleration= (vf-vi)/t(14.0 m/s) / 8.0s= .50m/s^2
A bicycle takes 8.0 seconds to accelerate at a constant rate from rest to a speed of 4.0 m/s. If the mass of the bicycle and rider together is 85 kg, what is the net force acting on the bicycle?
Momentum is always conserved in
A collision, either elastic or inelastic
Experiment
A scientific procedure to make a discovery
Momentum is
A vector, which means it has a magnitude and direction North and East - Positive South and West - Negative
Gymnast lands on a padded mat causing an increase in time by 5, the force on her body is
About 5 times less
recoil
Acceleration
The force your bumper car exerts on the other car is the action force. The force the other car exerts on your car is the reaction force. These two forces are equal in size and opposite in direction. Other examples: Pressing your hand against a wall and a hammer and a nail
Action and Reaction Forces
You may be wondering why the action and reaction forces acting on the swimmer do not cancel each other and produce a net force of zero. The reason is that the action and reaction forces do not act on the same object. Only when equal and opposite forces act on the same object do they result in a net force of zero
Action-Reaction Forces Do Not Cancel
Can you determine the action and reaction pair between a swimmer and the water? Unlike the swimmer in the previous example, not all action and reaction forces produce motion
Action-Reaction Forces and Motion
Is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.
Air Resistance
Impulse
Amount of force over time, a force acting over a period of time
Distance
An amount of space between 2 things
Give an example of an Inelastic collision.
An egg splats on the floor Permanent change in shape sound energy released objects stick together
Inertia
An objects resistance to motion
The ancient Greek Scientist and philosopher made many scientific discoveries through careful observation and logical reasoning. Aristotle incorrectly proposed that force is required to keep an object moving at constant speed. This error held back progress in the study of motion for almost 2 thousand years
Aristotle (384 BC - 322 BC)
Sometimes, the net force acting on an object is zero. Balanced forces are forces that combine to produce a net force of zero. When the forces on an object are balanced, the net force is zero and there is no change in the object's motion
Balanced Forces
During an inelastic collision, the resultant velocity will
Be slower because the mass increases
Momentum is increased when
Both mass and velocity are increased
A situation in which two objects in close contact exchange energy and momentum.
Collision
Under certain conditions, collisions obey the law of conservation of momentum. Conservation of Momentum does not increase or decrease. Imagine two cars colliding with one another. If the two cars are apart of a closed system, then momentum is conserved. A closed system means other objects and forces cannot enter or leave a system. Thus, if we consider the two cars as a closed system, the cars can exert forces on each other. But overall, the total momentum of the system is conserved. In a closed system, the loss of momentum of one object equals the gain in momentum of another object- momentum is conserved
Conservation of Momentum
The momentum of an object, or set of objects (system), remains the same if it is left alone. Within such a system, momentum is said to be conserved.
Conservation of momentum
The combination of an initial forward velocity and the downward vertical force of gravity causes the ball to follow a curved path.
Describe why a projectile follows a curved path.
-11 m/s^2
During a test crash, an airbag inflates to stop a dummy's forward motion. The dummy's mass is 75 kg. If the net force on the dummy is 825 N toward the rear of the car, what is the dummy's deceleration?
Earth's gravity acts downward toward the center of Earth.
Earth's gravitational force acts in what direction?
In the absence of external forces, momentum is conserved in
Either elastic or inelastic collisions
Two objects bounce off each other.
Elastic collision
Two objects bounce off each other.
Elastic collision: what it looks like
Kinetic Energy
Energy of motion
the measurement system used most commonly for everyday measurements in the US is the
English system
Lifting a 50 kg barbell 2.0 meters above the floor increases its potential energy by how much?
Ep=981J
Newton's Third Law of Motion
Every action has an equal reaction
Momentum notes
Every moving mass has it -inertia in motion
The amount of kinetic energy possessed by a 0.3 kg ball rolling at a speed of 4 m/s is how much?
Ex= 2.4J
Why is the Metric system used in science instead of the English system?
Factors of ten are easier to work with mathematically
Free Fall
Falling with no resistance
Pressure is defined as force per unit area. It is usually more convenient to use pressure rather than force to describe the influences upon fluid behavior. The standard unit for pressure is the Pascal, which is a Newton per square meter. Friction also acts on a submarine moving through water and on an airplane flying through the air. Water and a mixture of gases such as air are known as fluids.
Fluid Force
Strength or energy as an attribute of physical action or movement. It can cause a resting object to move, or it can accelerate a moving object by changing the object's speed or direction. Wind pushing against a person can cause them to slow down, or even change direction
Force
Impact force
Force that causes impulse
Force that opposes motion between two surfaces.
Friction
The resistance that one surface or object encounters when moving over another. All moving objects are considered this. It acts at the surface where objects are in constant contact. There are four main types which are: static, sliding, rolling, and fluid
Friction
kevin rolls a 9 kg bowling ball slowly that it stops. The impulse necessary to stop this bowling ball rolling at 3 m/s is?
Ft= -27 N.S
The impulse necessary to change the momentum of a 25 kg object by 3 kg*m/s is how much?
Ft= 75 N.S
A force can cause a resting object to move, or it can accelerate a moving object by changing the object speed or direction.
How is the motion of an object affected when a force acts on it?
Galileo studied motion by rolling balls down wooden ramps. He studied how gravity produces constant acceleration. Galileo concluded that moving objects not subjected to friction or any other force would continue to move indefinitely
Galileo (1564 - 1642)
Force that pulls all objects together "closer the objects, the harder the pull" "greater the mass, larger the pull"; acceleration due to gravity is 9.8 m/s/s on earth (if it weren't for air resistance).
Gravity
The force that attracts a body toward the center of the earth, or toward any other physical body having mass. For most purposes Newton's laws of gravity apply, with minor modifications to take the general theory of relativity into account. It is an attractive force, that is, it pulls objects together. Earth's gravitational force exerts a force of attraction on every other object that is near Earth. Earth's gravity acts downward toward the center of the Earth
Gravity
Greater impulse equals
Greater change in momentum
When a car comes to a full stop after hitting a brick wall and hitting a water filled barrel, the force that stops the momentum is: greater hitting the wall, greater hitting the barrel, the same momentum change in both.
Greater hitting the wall
The impulse needed to bring an object to a stop and then "throw it back again" (bounce) is
Greater than the impulse needed to stop the object
Superman and asteroid are both at rest in space, if superman throws the asteroid and it flies away at 8 m/s what will happen to him?
He will fly away faster
If Suzie doubles her sprinting velocity, what else doubles? p = mv
Her momentum
When air resistance acts, acceleration during a fall will be less than g because air resistance affects the motion of the falling objects by slowing it down.
How does air resistance affect the acceleration of a falling object?
Mass is a measurement of the amount of matter something contains, while Weight is the measurement of the pull of gravity on an object.
How is mass different from weight?
p = mv. If the mass is doubled and the velocity doubled, what happens to the momentum?
It quadruples
What is the first step in every physics problem?
Identify what the problem is asking.
The eagle. Because it has greater mass
If an eagle and a bumblebee are traveling at 8 km/hr, which has more momentum? Explain
Change in momentum
Impulse
M(Vi - Vo) or I = F(T)
Impulse Formulas
The momentum change of an object is equal to the
Impulse acting on it
If you hit a solid wall instead of a safer barrier, you would have a greater chance of injury because
Impulse force is large and impulse time is small
You have a less chance of being hurt if your speeding car hits a haystack instead of a mall because
Impulse force is small and impulse time is large
Change in momentum: term only
Impulse: definition
In order to increase the final momentum of a tennis ball, you need to
Increase the force acting upon it Follow through when hitting the ball Increase the time of contact
Two objects sticking to each other.
Inelastic Collision
Two objects sticking to each other.
Inelastic Collision: what it looks like
Only momentum is conserved. Kinetic Energy is lost in the forms of heat and sound
Inelastic Collisions conserves
A body at motion stays in motion unless acted on by an outside force and a body at rest stays at rest.
Inertia
A tendency to do nothing or to remain unchanged. Newton's first law of motion is sometimes called the law of inertia
Inertia
p = mv. If the mass is triples what happens to the momentum?
It triples
p = mv. If the mass is doubled what happens to the momentum?
It doubles
Football helmets are made with padding that helps reduce head injuries when a player collides with an object. Which best explains how the padding reduces injuries?
It extends the time of the collision
Football helmets are made with padding that helps reduce head injuries when a player collides with an object. Which best explains how the padding reduces injuries?
It extends the time of the collision.
What is the reason a cannon has a smaller recoil (acceleration) than a cannonball
It has a larger mass
Objects 1 and 2 collide and stick together. Which best describes the momentum of the resulting single object?
It is equal to the momentum of object 1 plus the momentum of object 2.
Large force over long time equals
Largest impulse
Momentum is not lost in a collision but can only be transferred
Law of Conservation of Momentum
the law that states that energy cannot be created or destroyed but can be changed from one form to another
Law of Conservation of Momentum
For a collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision
Law of conservation of momentum
Newton's First Law of Motion
Law of inertia
Static, sliding, rolling, and fluid friction.
List the four types of friction.
A coherent, typically large body of matter with no definite shape
Mass
The amount of matter in an object; SI unit for measuring mass is the kilogram.
Mass
When the mass is greater (at the same speeds), the momentum is greater. An object with a very small mass that has a lot of momentum because it is moving very quickly. MOMENTUM INCREASES WHEN EITHER MASS OR VELOCITY INCREASES!!
Mass and velocity and how it affects an object's momentum.
Momentum
Mass in motion, inertia in motion
Terminal Speed
Maximum speed an object can go in free fall
Forces are often easy to measure. The stretch of the spring in the scale depends on the amount of weight acting on it. Weight is a type of force
Measuring Force
Mass in motion; a measure of how hard it is to stop the object (p = m*v ---- kg x m/s).
Momentum
Momentum is the product of an object's mass and its velocity. The momentum for any object at rest is zero. You can calculate momentum by multiplying an object's mass(in kilograms) and its velocity(in meters per second). Momentum Formula Momentum = Mass x Velocity. Momentum is measured in units of kilogram-meters per second. (kg*m/s)
Momentum
kg•m/s.
Momentum (SI unit)
Momentum can be defined as "mass in motion." All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion.
Momentum (defined)
Momentum = Mass x Velocity
Momentum (formula)
Calculate the momentum of a 12ookg car with a velocity of 25m/s. p = mv = 1200 X 25 = 30,000kg.m/s
Momentum (practice problem #1)
A bowling ball of 35.2kg, generates 218 kg.m/s units of momentum. What is the velocity of the bowling ball? V = p/m = 218/35.2 = 6.2m/s
Momentum (practice problem #2)
A school bus traveling at 40 km/hr. (11.1m/s) has a momentum of 152625 kg.m/s. What is the mass of the bus? M = p/v = 152625/11.1 = 13,750kg
Momentum (practice problem #3)
p
Momentum (symbol)
Momentum is a measure of the ________ of an object.
Motion
Is the sum of all forces acting on an object. It is capable of accelerating a mass. For instance, if the wheels of a car push it forward with 5 Newtons and drag is 3 Newtons , the net force is 2 Newtons, forward. Like vectors, you can combine force arrows to show the result of how forces combine. Forces in the same direction add together and forces in opposite directions subtract from one another
Net force
The SI unit of force. It is equal to the force that would give a mass of one kilogram an acceleration of one meter per second per second, and is equivalent to 100,000 dynes. Force is measured in this, abbreviated as N. 1 N is equal to 1 kilogram-meter per second squared (1 N = 1 kg*m/s2). The Newton is named after Sir Isaac Newton
Newton
According to Newton's first law of motion, the state of motion of an object does not change as long as the net force acting on the object is zero. Thus, unless an unbalanced force acts, an object at rest remains at rest, and an object in motion remains in motion with the same speed and direction
Newton's First Law of Motion
An unbalanced force causes an object's velocity to change. In other words, the object accelerates. Newton also learned that the acceleration of an object depends upon its mass. According to Newton's second law of motion, the acceleration of an object is equal to the net force acting on it divided by the object's mass. Thus, doubling the mass of an object cuts its acceleration in half. The acceleration of an object is always in the same direction as the net force. Note that Newton's second law also applies when a net force acts in the direction opposite to the object's motion
Newton's Second Law of Motion
A force cannot exist alone. Forces always exist in pairs. According to Newton's third law of motion, whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object
Newton's Third Law
Momentum deals with
Newton's third law
A boy threw a powerade up to his girlfriend who was leaning out of the second-floor window, 12 meters up. The powerade stopped rising after 1.3 seconds. Did he throw the powerade high enough for her to catch it?
No
If nothing moves, then how much work is done?
None
Elastic collision
Objects bounce off one another without any deformation, sound, or generating heat
Inelastic collision
Objects stick together, they either distort or generate heat
Both Kinetic Energy and momentum are conserved
Perfectly Elastic Collision conserves
How can impulse affect the impact of a collision?
Reduce force of impact Make stopping time of impact longer
The law of conservation of momentum states that, if left alone, the total momentum of two interacting objects that make up a system .
Remains the same
You can use an arrow to represent the direction and strength of a force. The direction of the arrow represents the direction of the force. The length of the arrow represents the strength, or magnitude, of the force
Representing Force
Inertia
Resist changes in the state of motion
Is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. When a round object rolls across a flat floor, both the object and the floor are bent slightly out of shape. This change in shape at the point of contact is the cause of friction
Rolling Friction
After being forced to leave school because of a plague outbreak in London in 1665, Newton began to build on the work of scientists like Galileo. He published his results many years later in a book called Principia. In this work he defined mass and force, and also introduced his laws of motion
SIr Isaac Newton
Refers to the resistance created by two objects sliding against each other. This can also be called kinetic friction. It is intended to stop an object from moving. If you push an object and it begins to move, it is no longer acting on the object. Instead, a smaller friction force called this acts on the sliding object
Sliding Friction
A cannonball is launched from a cannon. The ACCELERATION on the cannon compared to the cannonball is
Smaller than on the cannonball
A cannonball is launched from a cannon. The CHANGE IN VELOCITY on the cannon compared to the cannonball is
Smaller than on the cannonball
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
State Newton's first law of motion in your own words.
It is written in equation form, p = mv, where p is momentum, m is mass in kg and v is velocity in m/s. Because momentum is a vector quantity, this means it has both magnitude and direction.
State in your own words the formula for momentum
Is the friction that exists between a stationary object and the surface on which it's resting. It always acts in the direction opposite to that of the applied force. You experience it every time you take a step
Static Friction
Potential Energy
Stored energy of position
If there are 2 cars with the same mass but one has doubled the speed
That car will have double the momentum
English System
The English set of units
Newton
The S.I. unit for force
Energy
The ability to cause change
When someone throws a ball, the action force is the person pushing on the ball. What is the reaction force?
The ball pushing the person
When 2 objects recoil, the objects have
The exact same momentum as each other
If the time is increased, what happens to the force that stops your momentum?
The force decreases.
S.I. System
The international set of units
A lunar vehicle is tested on Earth at a speed of 10 km/hr, driving at the same speed on the moon
The momentum is the same
Displacement
The moving of something from its place
A bowling ball collides with a pin and pushes the pin toward the right. Which describes the reaction force
The pin pushes the bowling ball toward the left
A bowling ball collides with a pin and pushes the pin toward the right. Which describes the reaction force?
The pin pushes the bowling ball toward the left.
Precision
The quality
Deceleration
The rate at which velocity decreases
Acceleration
The rate at which velocity increases
The chart lists the masses of four balls that have the same momentum. Which correctly compares two of the balls?
The red ball has a greater velocity than the purple ball
The chart lists the masses of four balls that have the same momentum. Which correctly compares two of the balls?
The red ball has a greater velocity than the purple ball.
A cannonball is launched from a cannon. The CHANGE IN MOMENTUM on the cannon compared to the cannonball is
The same
A cannonball is launched from a cannon. The FORCE on the cannon compared to the cannonball is
The same
Law of conservation of momentum
The total momentum remains constant, it can be transferred, not created nor destroyed Momentum is transferred when objects collide
Dependent Variable
The variable that changes due to the independent variable
Independent Variable
The variable that you change
According to Newton's third of motion, whenever an object exerts a force on a second object, the second object exerts an equal and opposite force on the other object. These two forces are called the action and reaction forces.
Using Newton's Third Law, explain what is meant by action and reaction pairs of forces
a penny dropped into a wishing well reaches the bottom in 2.4 seconds. What was the velocity at impact
V2=23.5 m/s
A boy whose mass is 37 kg runs at 5 m/s and jumps onto a 15 kg sled sitting still. The boy slides on the sled at a speed of what? (Find V 3)
V3= 3.6 m/s
A 3 kg piece of clay moving at 5 m/s strikes and sticks to a second 5 kg piece of clay moving at 2 m/s. Calculate the speed of the combined piece of clay. (Find V 3 )
V3=3.13 m/s
Carlie rides her bicycle 5.2 km up a steep hill in 7 minutes. What is her speed?
V= 0.74 km/min
Calculate the speed of your cat chasing a mouse 200 yards in 15 seconds
V= 13.3 yards/sec
If you know the distance and the time, what formula would you use to calculate the velocity?
V= d/t
The speed of the object and the direction of its motion.
Velocity
A body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.
Weight
A measure of the force of gravity pulling down on your body; unit for measuring weight is the Newton.
Weight
lthough related to each other, mass and weight are not the same. An object's weight is the product of the object's mass and acceleration due to gravity acting on it. Weight Formula. Weight = Mass x Acceleration due to gravity. W= mg. The value for g is 9.8 m/s2. Mass and weight are proportional. Doubling the mass of an object also doubles the object's weight. Mass is a measure of the inertia of an object; weight is a measure of the force of gravity acting on an object
Weight and Mass
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
What equation states Newton's second law of motion?
Constant value. Momentum does not increase or decrease
What is a necessary condition for the conservation of momentum?
Collision
When 2 or more objects come together (one must be moving)
The momentum of any object that is at rest is zero
When is momentum = Zero
Explosion
When one object becomes many moving objects
The object has mass, but it does not have any "mass in motion"
Why is the momentum of an object at rest equal to zero?
a position vs time graph that is a straight line could represent
an object with a constant velocity
Describe at what point velocity would be zero if you tossed a ball up in the air.
at the peak of the parabola
the unit of length that most nearly matches the width of your finger
centimeter
if he net force acting on a moving object is 0, what will the object do?
continue in the same direction with no change of speed
robin measures the force needed to pull a wagon up an incline as more weight is added. in this investigation weight is the ~what~ variable?
control
what isnt a unit for speed?
d/t
the term that best describes the motion of an object slowing down
deceleration
as the speed if a moving object doubles, the amount if mechanical kinetic energy that it possesses
decreases by four times
a change in position
displacement
in a motion experiment with a car on a track, the car moves 50 cm away from the origin, then moves 20 cm towards the origin. whats the cars displacement and distance traveled
displacement equals 30 cm and distance equals 70 cm
You are walking on a track. You move 40cm away from your origin, then turn around and come 20 cm back. What is your displacement, and your distance?
displacement=20cm distance 60cm
What is the constant for gravity?
g=9.81 m/s2
a 20-kilogram object falls 2.0 meters to the floor. at what point in its fall does the kinetic energy if a body equal its potential energy
halfway to the floor
a tentative, testable statement that attempts to explain a set of scientific observations
hypothesis
the first step in solving a physics problem is to
identify what the problem is asking
when an object is accelerating due to the force of gravity with no other forces acting on it, it is ____
in free fall
if an object is accelerating, what wont occur
it remains motionless
Anya knows the velocity of an object. What else does she need to know in order to find the object's momentum?
its mass
work may be measured using units of
joules
As the speed of an object doubles, what happens to the kinetic energy?
kinetic energy increases as the square of speed. Ex. Speed increases 2x so kinetic energy increases 2x2 (4x)
What are the units used for acceleration?
m/s2
units of measurement used it label a quantity of acceleration
m/s^2
units of measurement used to label a quantity of accelerations are
m/s^2
you push a box with a force of 35 N and the box accelerates at 3.5 m/s2
m=10kg
Jerome solves a problem using the law of conservation of momentum. What should Jerome always keep constant for each object after the objects collide and bounce apart?
mass
the inertia of an object is related to its
mass only
what is not an important part of studying physics?
memorizing complicated explanations
the impulse applied to an object is equal to the change in the objects
momentum
Momentum is a measure of the of an object.
motion
acceleration if an object must be caused by a force that is
not zero
Which formula can be used to express the law of conservation of momentum, where p = momentum?
p initial = p final
A 0.3 kg baseball thrown at a speed of 35 m/s, and a 8 kg bowling ball rolling at 3 m/s are both stopped in 0.5 seconds. Which ball is stopped with MORE force because it has MORE momentum?
p2 = 24 kg.m/s
calculate the momentum of a 2300kg car traveling at 25 m/s.
p= 57500 kg.m/s
Which formula can be used to express the law of conservation of momentum, where p = momentum?
pi = pf
energy that is stored due to the position of an object may be called _____ energy
potential
if an object is accelerated, what WONT it do?
remain motionless
The law of conservation of momentum states that, if left alone, the total momentum of two interacting objects that make up a system .
remains the same
the basic unit of time in both si and english system of measurement
second
Identify the basic unit of time in the SI and English Systems of measurement. seconds
seconds
what term in used to describe the meaningful digits in a measurement?
significant
How would you calculate the slope on a graph?
slope= rise/run
potential energy increases as
slows rolling up an incline
a 15 kg baseball is thrown at a speed of 50 meters per second and a 7.25 kg bowling ball rolling at 2 meters per second are both stopped in 0.2 seconds.
the baseball is stopped with less force because it had less momentum
while standing on a stationary skateboard, Jolene tosses a heavy ball horizontally towards one end of her skateboard. The skateboard moves. Assuming there is no friction in the system when the ball is tossed, which statement about the momentum of the heavy ball is incorrect?
the directions of the balls momentum and jolenes momentum are the same
terminal speed occurs when
the force of gravity is balanced by the air resistance of an object
the inertia of 2 objects must be the same if
the same force causes the same acceleration in both objects
kiki accidentally nudges a glass tumbler with her elbow and it falls toward a hard, ceramic tile floor. as a soccer player, Kiki reacts by catching the class with her foot and lowering it to the floor, preventing the glass from breaking. Her action prevents the breakage because:
the time interval for stopping is greater when kiki catches the class with her foot
Describe the relationship between "Impulse" and "Change in Momentum".
they are measuring the same thing
If you divide distance by speed, what are you calculating?
time
Kaitlin is pushing her little brother in a swing. If her little brother weighs 27 kg, how much higher does Kaitlin need to push him to increase his potential energy to 350 joules?
x= 1.32m
It takes a runner 3 seconds to accelerate to a speed of 6 m/s near the finish line of a race. If his acceleration is 1.5m/s 2 , what was his initial velocity?
x=1.5
What is the acceleration of a 1,600 kg car when a force of 5,200 N is applied?
x=3.25m/s2
A stone tumbles into a mine shaft and strikes bottom after falling for 5.7 seconds. How deep is the mine shaft?
y= 159.4m