Physics Final Exam

what is conserved when two railroad cars moving toward each other collide and move off together?

momentum

what is conserved when a diver is freely falling from some height to a lower height

energy

two college students having the same mass roll away from each other on roller blades, each moving at the same speed v. what is the combined momentum of the two skaters?

0

a job is done slowly, while an identical job is done quickly. both jobs require the same amount of work, but different amounts of

power

in which situation does the force of gravity do no work

a golf ball rolls along a level putting green

when an object is lifted three feet, it gains a certain amount of potential energy. if the same object is lifted six feet, its potential energy is

twice as much

a 12 N falling object encounters 3 N of air resistance. the net force on the object is

9 N

my wife and I walk our dogs a distance of about 1.5 miles in 30 minutes. this means our average walking speed is

three miles per hour

a car accelerates from rest at 3 m/s². what is its velocity three seconds after the car starts moving

9 m/s

if an object is traveling 50 km/hr, its speed in m/s would be

about 14 m/s

passenger side air bags in modern cars help reduce the _____ during an accident by increasing the time the passenger’s body interacts with the dashboard

force

by applying the brakes, she stopped the car. now the car’s ____ is zero

momentum

regardless of their velocities, a delivery truck always has more ____ than a mini cooper

inertia

it takes 2 seconds for a stone to fall to the ground from a rooftop. how high is the rooftop?

about 64 ft

if you are going 25 miles/hour and then accelerate at 2 miles/hour/second for five seconds, what is your final velocity?

35 miles/hour

you lurch forward in a bus that suddenly slows down. this illustrates

newton’s first law of motion: inertia

strange as it may seem, it is just as hard to accelerate a car on the moon as it is to accelerate the same car on earth. this is because

the mass of the car is independent of gravity

you fire a cannonball from a cannon. the magnitude of the force acting on the _____ is greater

the force is the same for both cannonball and cannon

you fire a cannonball from a cannon. the object to undergo the greater change in momentum will be the

both have the same change in momentum

a beach ball is thrown toward you. which situation requires you to exert the greater impulse on the ball

to let the ball bounce off your chest

which requires more work on a 40 kg sack of pebbles

to accelerate the sac from 20 m/s to 25 m/s

what is the direction of the force that acts on the clothes during the spin cycle of an automatic clothes washer

inward toward the center of rotation

the value of g at the earth’s surface is about 10 m/s². what is the value of g at a distance of three times the earth’s radius?

just a little more than 1 m/s²

a 1.5 kg rock is suspended from the tip of a meter stick at the 0 cm mark so that the meter stick balances like a seesaw when the fulcrum is at the 25 cm mark. from this information what is the mass of the meter stick

1.5 kg

the rotational inertia of your leg as you walk is greater when your leg is

straight

the time for a ball to fall straight to the ground from your hands is about 0.35 seconds. if you throw the ball straight ahead from the same height, the ball will reach the ground in

about 0.35 seconds

when gas in a container is squeezed to half its original volume and the temperature remains the same, the gas pressure

doubles

when a potato is cut in half, the density of each half is ____, and the volume of each half is ____

unchanged, half the original

a child at birth is about 20 inches long. by the time it grows to 40 inches tall, the weight of its body will increase by about

eight times

the chamber at right is connected to the manometer through a tube, pushing the lid down to point b and elevating the liquid in the manometer to a height h above point a. this means the pressure at point a is

the same as point B, equal to the chamber pressure, and equal to pgh

in the diagram to the right, under which piston is the force greater

the large piston

under which piston in the diagram is the pressure greater

both the same

a block of wood floats on water. this means the ___ of the water displaced equals ___ of the block

weight, weight

imagine a bamboo tube with a 1 in² area extending from the ground way out into space. how much would the air in the tube weigh

about 15 pounds

you see a truck driving down the freeway and there is a tarp stretched across the back of the truck. the tarp will be

bulging up above the back of the truck

which contributes more to the mass of an atom

protons

what would be the gravitational force on an 80 kg man who is standing on the surface of the planet mercury? the mass of mercury is 3.3 × 10²3 and its radius is 2.4 ×10^6 m.

300 N

a diver jumps off a 10 m high platform and does a bunch of flips. before he hits the water, he increases his rotational inertia by a factor of 2. his rotational speed will

increase by a factor of 4

a metal sphere with a radius of 2 cm has a mass of 270 g. its density is

about 8 grams/cm³

a 120 N force results in a pressure of 600 pascals. what is area over which the force is distributed

0.2 m²