Physics Final Exam
A 10-N falling object encounters 4 N of air resistance. The net force on the object is
(10-4) = 6N
Pour a liter of water at 40°C into a liter of water at 20°C and the final temperature of the two becomes
(40+20 =60/2= 30 c) at or about 30 degrees Celsius
A mosquito flying at 3m/s that encounters a breeze blowing at 3m/s in the opposite direction has a speed of
0m/s
A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration in meters per second per second is
0m/s2
A block pulled to the left with 15 N and to the right with 5 N at the same time experiences a net force of
10N
A bag of groceries that has a mass of 10 kilograms weighs about _____ N
1kg = 10N 10kg X X= 100N
According to newton, when the distance between two interacting objects doubles. The gravitational force ______
2 squared = 4 = 1/4 (inverse square law) Is one quarter
When a drawn bow of potential energy 40 J is fired, the arrow will ideally have a kinetic energy
40 J
Suzie Skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on Suzie is then
500N (for every action there is an equal and opposite reaction)
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of
6 m/s
If a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is
6 m/s^2
An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will A) move in the opposite direction at a lower speed B) move in the opposite direction at 20m/s C) move in the opposite direction at a higher speed D) none of the above
A) move in the opposite direction at a lower speed because W=mg and his mass is more than the ball.
The most basic of the sciences of physics, chemistry, and biology is A) physics. B) chemistry. C) biology. D) none of the above
A) physics
A circus diver drops from a high pole into water far below. When he is halfway down A) his kinetic energy and potential energy are equal B) he has gained an amount of KE equal to half his initial PE C) his potential energy has halted D) all the above
All the above
The earliest and most influential Greek philosopher was Aristotle, who among many contributions taught that A) the four elements are earth, water, air, and fire B) violent motion requires a sustained push or pull C) all motion is either natural or violent D) all the above
All the above
When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of
Average speed = distance / time 4m/s = x / 5 4(5) (5) X= 20 m
The average speed of a horse that gallops 10 kilometers in 30 minutes is___km/hr
Average speed = distance/ time Average speed = 10km/.5hour Average speed = 20km/h
Which of the following has the largest momentum relative to Earth's surface ? A) a mouse running across your room B) a pickup truck speeding along a highway C) the science building on campus D) a Mack truck parked in a parking lot E) a tightrope walker crossing Niagara Falls
B) a pickup truck speeding along a highway
Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is A) greater with the haystack B) both the same C) greater with the brick wall
B) both the same. The impulse remains the same.
A theory in the field of science is A) an educated guess. B) less than a fact. C) a synthesis of a large body of well-tested knowledge. D) unchangeable.
C) a synthesis of a large body of well-tested knowledge
The lower the temperature of an object the A) longer the waves B) lower the frequency of the radiation it emits C) all of these
C) both of these
Which temperature scales have equal sized degrees ?
Celsius to Kelvin
The first scientist to be credited for postulating that Earth circled the sun was
Copernicus
Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter A) shorter time of contact B) increased momentum C) decreased impulse D) lengthened time of contact
D) lengthened time of contact because ⬆️ time of contact ⬇️force.
According to Kepler, the paths of planets around the sun are
Ellipses
A bird flying at 8 km/h in a 6-km/h crosswind has a resultant speed of
F= 8^2 + 6^2 = 100 square root 100= 10km/h
Danny Diver weighs 500 N and steps off a diving board 10 m above the water. Danny hits the water with kinetic energy of
F= w• d F= 500N • 10m F= 5,000J
What is the force of gravity on a 500-N woman standing on Earth's surface?
F=mg F= 500N
A tow truck exerts a force of 3000 N on a car, which then accelerates at 2 m/s2. What is the mass of the car?
F=m•a 3000N = m•2m/s2 /2 /2 1500kg = m
A car has a mass of 1000 kg and accelerates at 2 m/s2. What net force is exerted on the car?
F=m•a F= 1000kg• 2m/s F= 2000N
The total momentum of a flock of identical birds could be zero only if the birds are A) taking off from the ground B) very tired and coming down to rest C) flying in different directions D) flying in the same direction
Flying in different directions. Total momentum =0 because ⬅️+ 4. -4➡️ 4+ -4 = 0
It is correct to say that impulse is equal to A) force multiplied by the distance it acts on B) momentum C) velocity multiples by time D) the corresponding change in momentum
F•t = mVf - mVo (Impulse) (Change in momentum)
The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is A) 3000N B) 4000N C) 5000N D) 2000N E) 1000N
F•t = m•v M= 1000kg V= 10m/s t= 5s F• (5) = (1000)(10) 10,000 /5 /5 F= 2000N
According to Newton, the greater the masses go interacting objects the
Greater the gravitational force between them
While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its vertical component of velocity
Increases
Gelileo taught us that if you roll a ball along a level surface it will
Keep rolling if friction is absent
A same-size iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater
Momentum
A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is A) Equal to its weight divided by its mass B) Equal to its weight C) Equal to urs mass times it's weight D) none of the above
None of the above
Communications and weather satellites always appears the same place in the sky becaus these satellites are
Orbiting the earth with a 24-hour period
A 2-kg ball is held 4 m above the ground. Relative to the ground its potential energy is
PE= m • g • h PE= 2 • 10 • 4 PE= 80J
The power expended doing 100 J of work in 50 s is
Power= energy(j)/time(s) Power = 100/50 Power = 2WATTS
Nellie tosses a ball upward at an angle. Neglecting air resistance, the horizontal component of the initial velocity
Remains constant
While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its vertical component of velocity
Remains unchanged
Galileo's use of inclined planes allows him to effectively
Slow down the balls change in speed
Which of the following is not a vector quantity
Speed
An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward at an angle instead, its acceleration will be
The same, g is constant
In comparison with other fundamental forces, the universal gravitational constant G indicates that gravity is
Very weak
The work you do when pushing a shopping cart twice as far while applying twice the force is
W= 2f • 2d = 4x So four times as much.
The work done in pushing a TV set a distance of 2 m with an average force of 20 N is
W= F•d W= 20N • 2m W= 40 J
The net force on any object in equilibrium is
Zero
A dropped ball gains speed because
a gravitational force acts on it
A package falls off a truck that is moving at 30 m/s. Neglecting air resistance, the horizontal speed of the package just before it hits the ground is
about 30 m/s
If an apple experiences a constant net force, it will have a constant
acceleration
Science is a body of knowledge that A) describes order in nature B) condenses knowledge into testable laws C) is an ongoing human activity D) all of the above
all of the above
Facts in the field of science
are changeable
If an object moves with constant acceleration, its velocity must
change by the same amount each second
If no external forces are acting on a moving object, it will
continue moving at the same speed
If a volume of air is warmed, it expands. If a volume of air expands, it
cools
Nellie tosses a ball upward at an angle. Neglecting air resistance, the vertical component of the initial velocity
decreases with time to reach the top.
The unit kilowatt-hour is a unit of
energy
The force that propels a cannonball when fired from a cannon is
equal and opposite to the force the ball exerts on the cannon
The force with which Earth pulls on the Moon is
equal in magnitude to the force that Moon pulls on Earth.
When a rocket forces exhaust gases downward, the exhaust gases
exert an upward force on the rocket
Science later greatly advanced when Galileo favored
experiment over philosophical discussions
Pseudoscience is best characterized as being
fake
When you drop a rubber ball on the floor it bounces back. The force exerted on the ball to produce bouncing is by the
floor
Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to
follow a straight-line path
An Earth satellite is simply a projectile
freely falling around the earth
When you touch a hot potato with your finger, energy flows
from the potato to your finger
As a ball bounces from a floor, its acceleration off the floor between bounces is
g
A ball is tossed upward. Neglecting air drag, the acceleration along its path is
g downward
The scientific method is most effective in
gaining, organizing, and applying new knowledge
Suspend your body from a pair of vertical ropes and the tension in each rope will be
half your weight
When Joshua brakes his speeding bicycle to a stop, kinetic energy is transformed to
heat
An educated scientific guess is a
hypothesis
Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them
increases
A sheet of paper can be quickly jerked beneath a container of milk without toppling, which best demonstrates
inertia
If the net force on a cart is tripled, the cart's acceleration
is three times as much
Temperature is most closely related to molecular
kinetic energy
A force is a vector quantity because it has both
magnitude and direction
An object that has kinetic energy must be
moving
To produce an acceleration to a system there
must be a net force on the system
A ball rolled along a horizontal surface maintains a constant speed because
no horizontal forces act on it
The force of Earth's gravity on a capsule in space will lessen as it moves farther away. If the capsule moves to twice its distance, the force toward Earth becomes
one fourth
The mass of a ball moving at 3 m/s with a momentum of 48 kg m/s is
p=m•v 48m/s = m • 3m/s /3 /3 M= 16kg
Compared to the mass of an apple on Earth, the mass of the apple on the Moon is
same
Sun's radiant energy is composed of shorter wavelengths than Earth's due to Sun's greater
surface temperature
Heat energy travels from an object with a high
temperature to an object with a lower temperature
Newton discovered
that gravity is universal
No work is done by gravity on a bowling ball that rolls along a bowling alley because
the force on the ball is at right angles to the ball's motion
To say there is no such thing as only one force means
there must also be a corresponding reaction force
The fact that a thermometer "takes its own temperature" illustrates
thermal equilibrium
Earth pulls on the moon, and the moon pulls on the earth, which tells us that
these two pulls comprise an action-reaction pair.
The kind of molecular motion that mostly relates to the temperature of a substance is
translational motion
A crate of grapes lifted 10 meters gains 200 J of potential energy. If the same crate is instead lifted 20 meters, its gain in potential energy is
twice as much
Nellie tosses a ball upward at an angle. Assuming no air resistance, which component of velocity changes with time?
vertical component
A bloc of wood and a block of copper will feel neither hot nor cold to the touch wen they each have
your temperature
A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is
zero
A weight watcher who normally weighs 400 N stands on top of a very tall ladder so she is one Earth radius above the Earth's surface. How much would she weigh there?
|_____|______|🌎 1 distance = 2d from earth = 2 squares = 1/4 sooooo 400n • 1/4 = 100N