phys 107 final
Two billiard balls of the same mass roll straight toward each other. The first has a velocity of + 5 m/s and the second has a velocity of -3 m/s. After colliding, the second ball has a velocity of
+5 m/s
A falling skydiver of mass 100 kg experiences 800 N air resistance. The acceleration of the skydiver is
.2 g
Buoyant force is greatest on a submerged
1 kg block of alumninum
On a balanced see saw, a boy three times as heavy as his partner sits
1/3 the distance from the fulcrum
The gain in speed each second for a freely falling object is about
10 m/s
If two 5 pound forces pull on an object in opposite directions, the net force is
10 pounds
If two 5 pound forces pull on an object in the same direction, the magnitude of the net force is
10 pounds
What is the weight of water displaced by a 100 ton floating ship
100 tons
A baseball player bats a ball with a force of 1000 N. The reaction force that the ball exerts against the bat is
1000 N.
A tow truck exerts a force of 3000 N on a car accelerating it at 3 meters per second per second. What is the mass of the car?
1000 kg
How much force does an M-16 rifle apply to a .01 kg cartidge if the cartridge is pushed out of the rifle in .001 s with a muzzle velocity of 1000 m/s?
10000 N
A worker with a mass of 150 kg stands on a 50 kg platform suspended at rest by two ropes. The tension in the first rope is measured to be 600 N. What is the tension in the second rope?
1400 N
A car moving at 30 km/hr skids 10 m with locked brakes. How far will the car skid with locked brakes if it were traveling at 120 km/hr?
160 m
A 2 kg mass has 40 J of potential energy with respect to the ground. Approximately how high is it above the ground?
2 m
A 5 kg shark swimming at a speed of 1 m/s swallows an absent minded 1 kg fish swimming toward it at 1 m/s. The speed of the shark after this meal is
2/3 m/s
If I need my machine to put out at least 40 Watts of power, and the most input power I can provide is 160 Watts, then my machine's efficiency needs to be at least
25%
Disregarding air drag, how fast must you toss a ball straight up in order for it to take 6 seconds to return to the level from which you tossed it?
30 m/s
What is the speed of a .2 kg softball if it has 90 J of kinetic energy?
30 m/s
If you need to tighten a bolt with 80 Nm of torque using a wrench with a handle that is 25 cm from the axis of the bolt, how much force do you need to apply when turning the wrench?
320 N
A tow truck accelerates a 1000 kg car that is towing at 4 meters per second per second. What is the force that the tow truck exerts on the car?
4000 N
What is the mass of an object if it gained 9000 J of potential energy after being lifted 20 m?
45 kg
A car travels 30 mi/hr for 30 minutes, the travels 60 mi/hr for 30 minutes. What is the average speed for the entire trip?
45 mi/hr
How much work is done on a crate as it slides 10 m across the floor at a constant velocity of 2 m/s?
5 J
To do 10 J of work pushing a crate using 2 N of force, you will need to push the crate
5 m
A 5 kg fish swimming at a speed of 1 m/s swallows an absent-minded 1 kg fish at rest. The speed of the larger fish after this lunch is
5/6 m/s
If a 100 kg wagon accelerates at 3 m/s^2 when a horse pulls it with 800 N of force, how much friction force is there on the wagon?
500 N
A 50 kg diver steps off a diving board that is 10 m above the water. The diver hits the water with kinetic energy of
5000 J
A car travels 30 mi/hr for 30 miles, the travels 60 mi/hr for 30 miles. What is the average speed for the entire trip?
60 mi/hr
If a 200 kg wagon accelerates at 2 m/s^2 when a horse pulls it with 1000 N of force, how much friction force is there on the wagon?
600 N
A worker with a weight of 1000 N stands on a 500 N platform suspended at rest by two ropes. The tension in the first rope is measured to be 700 N. What is the tension in the second rope?
800 N
A car moving at 50 km/hr skids 20 m with locked brakes. How far will the car skid with locked brakes if it were traveling at 150 km/hr?
90 m
An egg tossed into a pan smashes upon impact. An egg tossed into a sheet can not be broken because it experiences
A and C (increased time of impact and decreased impact force)
Which of the following concepts was first proposed by Galileo?
A force is required to change the motion of an object
A skydiver falls toward a lake on the Earth. The attraction of the Earth on the diver pulls the diver down. What is the reaction of this force?
Air resistance pushing the diver up
A car travels in a circle with constant speed. The net force on the car is
Directed towards the center of the curve
A Mack truck and a Volkswagen traveling at the same speed have a head -on collision. The vehicle that undergoes the least acceleration will be the
Mack truck
Consider a man standing behind a car pushing it without being able to move the car. Which of the following are an action-reaction force pair?
Man pushing the car and the friction of the road pushing the car
Which of these statements is true?
Molecules are made up of about 100 distinct chemical elements
About what percentage of the molecules that make up the atmosphere are below an aircraft that flies at an altitude of 6 kilometers?
More that 50%
When a rocket ship accelerating in outer space runs out of fuel it
No longer accelerates
A heavy truck and a light truck roll down a hill. Neglecting friction, at the bottom of the hill, the light truck will have greater
None of these
Which of the following theories was first published by Copernicus
None of these
If a crate is pushed across the floor with a force of 50 N and it is slowing down, how much is the friction acting on the crate?
Slightly more than 50 N.
A hydraulic press, like a properly arranged simple leaver, is capable of multiplying force input.
Sometimes true
Which of the following concepts was not first established by Galileo?
The Earth circles the sun
A running back carrying the football is about to be stopped in his tracks by one of two defenders: a 180 lb safety or a 320 lb lineman. All three players have the same momentum. Which defender will likely inflict the most pain on the running back, and why?
The lineman, because he has a greater inertia
Which of the following descriptions of an object's state is not equivalent to the others?
The net force on the object equals zero
A completely submerged object always displaces its own
Volume of fluid
It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
about 180 m
It takes 4 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
about 80 m
The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is
above a place of support
A woman alleviates her back pain in the fifth month of pregnancy by wearing a backpack instead of carrying a purse. When the pain resurfaces in the ninth month o pregnancy, she can reduce the back pain once again by
all of the above
A simple lever, properly arranged, is capable of multiplying work input
always false
When doing somersaults, you'll more easily rotate when your body is
balled up
According to Aristotle, the natural tendency of an object is to
be at rest
A heavy truck and a light truck roll down a hill. Neglecting friction, at the bottom of the hill, the heavy truck will have greater
both of these (kinetic energy and momentum)
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 velocity
A skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration
decreases
The volume of matter comes mostly from its
electrons
Two pool balls, each moving at 2 m/s, roll toward each other and collide. Suppose after bouncing apart, each moves at 4 m/s. This collision violates conservation of
energy
A truck is moving at constant velocity. Inside the storage compartment, a rock is dropped from the midpoint of the ceiling and strikes the floor below.. The rock hits the floor
exactly below the midpoint of the ceiling
During an eclipse of the sun the high ocean tides on Earth are
extra high
A skydiver is weightless when she
first steps out of the plane
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
Consider drops of water that leak at a steady rate from a dripping faucet. As the drops fall they
get farther apart
An object is propelled along a straight-line path by a force. If the net force were halved, the object's acceleration would
halve
Two objects of the same size, but unequal weights are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the
heavier object
If you add one proton to the nucleus of a common hydrogen atom, you get
helium
When a boat sails from fresh water to salt water, the boat will float
higher in the water
The chef at the infamous Fattening Tower of Pizza tosses a spinning disk of uncooked pizza dough into the air. The disk's diameter increases during the flight, while its rotation speed
increases
A man tries to catch a home run baseball while sitting in the outfield bleachers. Unfortunately, the ball misses his glove and hits the top of his head. If the ball bounces off his head, he will be hit ( ) he would if the ball sticks to his head
less hard than
In class, a wooden block was suspended from above by a string. A second string attached to the bottom of the block hung below. When the lower string was pulled slowly, the upper string broke. This is illustrated the block's
mass
A heavy truck and a light truck roll down a hill. Neglecting friction, at the bottom of the hill, the heavy truck will have greater
momentum
In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the
moon
As a balloon rises higher and higher into the atmosphere, its
none of these
Atoms heavier than hydrogen were made by
nuclear fission
The maximum acceleration of a car while towing a second car three times its mass, compared to its acceleration with no car in tow, is
one fourth
Doing twice the usual work on an object in four times the usual time requires
one half the usual power
Your pet hamster sits on a spinning record player. If the angular speed of the record player doubles and he moves to a point twice as far from the center, then his linear speed (assuming he doesn't fly off the record player and onto the floor, causing PETA and SPCA to come after you)
quadruples
Centrifugal forces are an apparent reality to observers in a reference frame that is
rotating
If the polar icecaps melted, the resulting water would spread over the entire earth. This new mass distribution would tend to make the length of a day
shorter
When braking a car in an emergency, one does not want to jam the brakes and make the tires lock because
static friction is greater than sliding friction
When a book is lying at rest on a table, the table exerts a force on the book to balance the force of gravity. The force that the table exerts is called thed
support force
Newton discovered
that gravity is universal
A ball rolling down an incline has its maximum kinetic energy at
the bottom
It is correct to say that impulse is equal to
the change in momentum
Arnold Strongman and Suzie Small each pull very hard on opposite ends of a massless rope in a tug-of-war. Suzie will win if
the ground pushes Arnold harder than he pushes the ground
Which is most responsible for the ocean tides?
the moon
When hammering a nail into a board, the action force is the head of the hammer hitting the nail. The reaction to this force is
the nail hitting the hammer.
What makes an element distinct?
the number of protons
An automobile and a baby carriage traveling at the same speed collide head-on. The impact force is
the same
Compared to the mass of a certain object on Earth, the mass of the same object on the moon is
the same
Consider two planets in space that gravitationally attract each other. If the mass of one of the planets is halved, and the distance between them is halved, then the force between them is
twice as much
In which situation does a long, thin, round metal pole have greater angular momentum?
twirling like a baton about the center of its length with an angular speed of 2 RPM
A dam is thicker at the bottom than the top partly because
water pressure is greater with increasing depth
if one object has three times as much mass as another object, it also must have three times as much
weight
When a falling object has reached its terminal velocity, its acceleration is
zero
