physics midterm
Name 6 different types of energy?
Sound Chemical Radiant Electric Atomic Mechanical
What is an object moving only under the influence of gravity?
projectile
What is made of a rope that passes over a wheel?
pulley
Sometime in rhe past semester, something has happened and you have thought "that's physics!" Describe the situation and the physics involved. Did you share this with those around you? How did they react?
really anytime it made sense. a lot of it was learning why certain things, we've been experiencing all our lives, happen
What is the force exerted by the machine on an object?
resistance force
What is the single vector that is the result of two or more vectors?
resultant
When we study projectile motion we refer to the horizontal part and the vertical part of the motion. What are these parts called?
satellite
What is a quantity that can be described by magnitude only?
scalor
What is the search for patters and relationships to explain and predict natural events?
science
What is an inclined plane that is wrapped around a rod or cylinder?
screw
What is the distance an object travels per unit of time?
speed
What is the type of equilibrium when objects are at rest?
static equilibrium
What is the upward force that balances the weight of an object on a surface?
support force
(true or false) When you slam on your brakes, your car accelerates.
true
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. What is the speed of the tangled cars after the collision?
(9000)(24)+(3000)(0)=(9000+3000)(V)=18m/s
You are sitting in a car that is not moving. You toss a ball up in the air and catch it. At the top of its path, what is the acceleration of the ball?
0
You are sitting in a car that is not moving. You toss a ball up in the air and catch it. At the top of its path, what is the speed of the ball?
0
What is the equation for kinetic energy?
1/2m•s^2
A physics book weighs 10N. If the book is sitting on your desk, what is the magnitude of the support force acting on the book? How do you know?
10N because every force has an equal opposite reaction, so a force 10N down would have to be matched by 10N up.
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. If the collision lasts 0.3 s, what is car A's acceleration during the collision?
18-0/.3 = 60m/s^2
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. If the collision lasts 0.3 s, what is the car B's acceleration during the collision?
18-24/.3 = -20m/s^2
What is the minimum net force that may be acting on you?
20N
To push a student and her chair takes about 30N of force. If this room is 8.0 meters wide, how much work is done to push the student and her chair the width of this room?
240 J
Your car goes from 20 m/s to 32 m/s in 4 seconds. What is the acceleration?
3 m/s
If you weigh 600 N, how much power is required for you to run up the stairs a distance of 10 meters in 20 seconds?
300 w
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. Calculate the amount of force that was applied to car B during the collision.
3000•60=180,000N
Your car goes from 0 m/s to 20 m/s in 5 seconds. What is acceleration?
4 m/s
While using a bumper jack to change a flat tire, a Physics student realizes that she is using only 150N of force to lift the back of a car that weighs 6000N. What is the mechanical advantage of the bumper jack?
40
Mr. Bowman dangles a 500N physics student off the roof of the school. If the roof is 8.0 m high, what is the student's potential energy?
4000 J
You are pushing your Physics book across the desk at a constant speed with a force of 4N. What is the magnitude of the friction acting on the book? How do you know?
4N because it would be opposing the force to move it because every force has an equal opposite reaction.
What is the kinetic energy of a 4 kg shot put that is moving through the air at a speed of 5 m/s
50 J
If you have a mass of 55kg, what is your weight in newtons?
539
You drive from Louisville to Orlando which is 990 miles away. If the trip takes 18 hours, what is your average speed?
55 mph
You are holding a ruler with a weight hanging off it. The weight and ruler together weigh 15N. You put a scale on each end of the ruler. The scale in your left hand reads 9N. What is the reading on the right scale? How do you know?
6 because the maximum weight possible is 15, and we know that one side weighs 9, so there is only 6N left before the max weight is hit.
A physics student realizes that she is putting 80 J of work into a machine, but is getting only 60 J of work out of it. What is the efficiency of the machine?
75%
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. Calculate the amount of force that was applied to car A during the collision.
8000•-20=-180,000N
What is the maximum net force that may be acting on you?
80N
When is Isaac Newton's birthday?
December 25
Use Newton's Laws to explain your answers to the previous two questions: When a car is sitting still, what forces act on the car? What is the net force acting on the car? A car is moving at a constant speed of 70mph on a straight flat road. What forces act on the car? What net forces act on the car?
THE LAW OF INERTIA (1) These cars are staying either in motion or still because there are no forces acting on them. this relates to newton's first law of motion, or the law of inertia.
Modern cars have air bags and crumple zones. How do these people protect the people in the car during collisions?
The bags lengthen the time of the impact, thus decreasing the amount of injury to the person
Give an example of two things that are inversely proportional and explain why.
The more people who help, the less time it takes
Give an example of two things that are directly proportional and explain why.
The number of toes increases with the number of feet The number of ears increases with the number of heads
Which of the following would be considered projectiles? a.) a helicopter landing b.) a skier going off a ski jump c.) a bullet fired from a rifle d.) a dropped feather e.) a flying bird f.) a mercy girl in the high jump
b c f
What is the acceleration of an object in free fall?
about 10 meters per square second
What is the change of velocity?
acceleration
What is the friction on an object moving through the air?
air resistance
State Newton's First Law of Motion
an object at rest tends to stay at rest until or unless acted upon by an unbalanced force. likewise, an object in motion tends to stay in motion until or unless acted upon by an unbalanced force.
What is the rate at which work is done?
power
Who was the first person to publicly state that the Earth revolves around the sun?
copernicus
What is the ratio of the work output of a machine to the work put into a machine?
efficiency
What is the force that you apply to a machine?
effort force
What is the ability to do work?
energy
What is a state where there is no change of motion?
equilibrium
What is the same about a ball's motion when the car is moving vs when the car is still?
everything is the same
(true or false) When you go around a curve, as long as you keep the same you are not accelerating
false
What is the general name for any substance that flows. It may be liquid or gas.
fluid
What is a push or a pull on an object?
force
What is a push or pull on an object?
force
What is the equation that defines Newton's Second Law of Motion?
force = mass x acceleration
What is your point of view when measuring motion
frame of reference
What happens when an object moves only under the influence of gravity?
free fall
What is a force that prevents the relative motion of two surfaces in contact with each other?
friction
What is the force acting between two surfaces in contact that tends to oppose motion?
friction
What is the fixed point at which a lever pivots?
fulcrum
Who was the person who used balls rolling down inclined ramps to reason that motion is changed only by force?
galileo
You are riding on the interstate at 70mph. You toss a ball up in the air. What forces are acting on the ball?
gravity
You are sitting in a car that is not moving. You toss a ball up in the air and catch it. What forces are acting on the ball?
gravity
When a car is sitting still, what forces act on the car? What is the net force acting on the car?
gravity is acting on a still car. the net force is 0 because it is not moving
What are the two factors that determine the amount of friction acting on an object?
how smooth/rough the object it force put on an object
You are riding on the interstate at 70mph. You toss a ball up in the air. Can you catch it or will it land behind you? Explain.
i can catch the ball because it is moving with the bus that i am sitting on
What is a slanted surface used to raise objects?
inclined plane
What is the term for resistance of an object to any change in its motion?
inertia
What is your velocity at a single instant?
instantaneous speed
What is the metric unit for kinetic or potential energy?
joule
What is the metric unit for work?
joule
What is the energy of motion?
kinetic energy
What states that energy cannot be created or destroyed, but can be transformed from one form to another?
law of conservation of energy
What is a bar that is free to pivot about a fixed point?
lever
Of the six types of simple machines, name one that is considered one of the basic types.
lever inclined plane
What is a device that changes the magnitude, direction or speed of a force?
machine
What is the mesure of the amount of matter in an object?
mass
What is the number of times a machine multiples the effort force?
mechanical advantage
What is the branch of physics that studies the effects of forces on objects?
mechanics
What is the displacement of an object compared to objects that are considered stationary?
movement
What is the combination of all of the forces acting on an object?
net force
What does this mean: EF=0?
net force = 0
What is the basic unit of force in the metric system?
newton
State Newton's Second Law of Motion.
newtons second law is: force = mass + acceleration
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. Did the momentum of the two cars together change? Why or why not?
no
What is the force pressing two surfaces together that acts perpendicular to the surfaces?
normal force
What is the name Aristotle gave to any motion that is straight up or straight down.
normal motion
What is different about a ball's motion when the car is moving vs when the car is still?
nothing would change, because regardless you are on the bus so you are moving with the bus
What is the science that studies energy and is effects?
physics
What is energy that is stored due to the condition or position of an object?
potential enegy
What is the stretching force on a string or spring?
tension
What is the velocity at which a falling object no longer accelerates because gravity and air resistance are balanced?
terminal velocity
What if a ball goes out the window of a car? Describe its motion.
the ball would drop just like normal, maybe a little further back depending on the speed of the car. in reference to the car, the ball would go backwards but in reference to a tree, it would just drop down.
A car slams on the brakes and skids to a stop. What forces act on the car? What net force acts on the car?
the weight of the car & the road friction the net force is whatever the friction is
A car is moving at a constant speed of 70mph on a straight flat road. What forces act on the car? What net forces act on the car?
there are no forces besides the gravity because it is staying in motion. the net force is 0 because it is not moving.
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. Which car experiences more force?
they experience the same force, just in oppose directions because they are exerting forces on each other
The roof of the school is 5 meters high. A ball is dropped off the roof of the school. Another ball is thrown horizontally off the roof. Which hits the ground first? Explain your answer.
they would both hit the ground at the same time because of gravity. gravity would be different on both objects, bur would affect both (and all other) objects in the same way.
"Motion is relative." What does this mean? Use examples.
this means that all motion is relative to another object. so if you're in a car, you're moving relative to a tree, but not relative to the driver of the car.
(true or false) When you swim across a river, your actual velocity is faster than when you swim across a lake?
true
What is a quantity that has both magnitude and direction?
vector
What is an arrow representing the magnitude and the direction of a quantity such as force?
vector
What includes speed and direction?
velocity
What is the name Aristotle gave to any motion that was not straight up or straight down.
violent motion
What is the metric unit for power?
watt
What is an inclined plane that consists of two sloping sides?
wedge
What is the measure of the force of gravity acting on an object?
weight
What is the equation for gravitational potential energy?
weight • height
What is the simple machine that consists of a large wheel attached to a smaller wheel or shaft?
wheel & axle
What is done when a force moves an object over a distance?
work
What is the equation to compute the amount of work that is done?
work = force • distance
What is the equation to compute the amount of power that is used?
work/time
You are sitting in a car that is not moving. You toss a ball up in the air and catch it. Is the ball accelerating? Justify your answer.
yes
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. Did car A accelerate? Why?
yes because it went from 0m/s to 18m/s
3000kg car A is sitting at a red light. 9000kg car B going 24 m/s runs into it. Did car B accelerate? Why?
yes because it went from 24m/s to 18m/s
You are riding on the interstate at 70mph. You toss a ball up in the air. Is the ball accelerating? Justify your answer.
yes, the speed decreases while it is thrown but then increases while it comes back down