physical science - physics - element 2 inertia, energy, gravity

a 5000 kg freight car crashes into a 10,000 kg freight car at rest. they couple upon collision and move with a speed of 2 m/s. what was the initial speed of the 5000 kg freight car?

6 m/s

a 100-kg astronaut ejects 0.1 kg of gas at a speed of 50 m/s from her propulsion pistol, her recoil speed is

0.05 m/s

What is the speed of a 4 kg ball with a momentum of 12 kg m/s?

3 m/s

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will

a lower speed

The greater efficiency achieved with the curved blades of a Pelton wheel is due to

bouncing

a supplier wants to make a profit by buying gold by weight at one altitude and selling it at the same price per newton at another altitude. the supplier should

buy at high altitude and sell at low altitude

a freight train rolls along a track with considerable momentum. if it rolls at the same speed but has twice as much mass, its momentum

doubled

the amount of gravitational force that acts on a space vehicle that orbits earth is

nearly as much as the vehicle's weight on earths surface

a sandbag is motionless in outer space. a second sandbag with 3 times the mass moving at 12 m/s collides with it and they both stick together and move at a speed of

none of these

the power expended for a barbell raised 2.0 m in 2s is

not enough informaiton

work is done by gravity on a bowling ball that rolls

on a sloped surface

If you push for an hour against a stationary wall, you do no work

on the wall

consider a gun with a pellet that is more massive than the gun. the firing speed is greater for the

recoiling gun

Newton discovered

that gravity is universal

which has greater kinetic energy: a car traveling at 30 km/h or another car of half the mass traveling at 60 km/h?

the 60 km/h car

After rolling halfway down an incline, a marble's kinetic energy is

the same as its potential energy

a karate expert executes a swift blow and breaks a cement block with her bare hand. the magnitude of the force on her hand is

the same as the force applied to the cement block

just after a big fish swallows a small fish, the momentum of the two-fish system is

the same before and after lunch

When a boxer is moving away from a punch, the force experienced is reduced because

the time of contact is increased

A ball rolling down an incline has its maximum potential energy at

the top

to catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. doing this reduces the catching force because the

time of catch is increased

perturbations of planets are due to

interplanetary forces

a melon is projected into the air with 100 J of kinetic energy in the presence of air resistance. when it returns to its initial level its kinetic energy is

less than 100 J

a piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball initially at rest. after the putty sticks to the ball, both move with a combined momentum of

1 unit

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 lunch is

5/6 m/s

In raising a 5000 N piano with a pulley system, it is noted that for every 1 m of rope pulled down, the piano rises 0.1 m. Ideally, this means the force needed to lift it is about

500 N

a 2 kg mass weighs 20 N and is held 4 m above the ground. its potential energy relative to the ground is

80 J

When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of the contact about 10 times that of a stiff-legged landing. In this way the average force your body experiences is reduced by

about 10 times

a moving object has

all of the above - speed, energy, momentum, velocity

if the radius of the earth somehow increased with no change in mass, your weight would

decrease

the distinction between impulse and force involves the

time the force acts

a 1 kg chunk of putty moving at 1 m/s collides and sticks to a 5 kg bowling ball initially at rest. the bowling call and putty move with a momentum of

1 kg m/s

a 1 kg glider and a 2 kg glider both slide toward each other at 1 m's on an air track. when they collide and stick, the combined glider speed is

1/3 m/s

It takes 40 J to push a large crate 4 m across a floor. The force exerted on the crate is

10 N

from the edge of a roof you throw a snowball downward that strikes the ground with 100 J of kinetic energy. then you throw a second snowball upward at the same initial speed, and this too falls to the ground. neglecting air resistance, the second snowball hits the ground with a kinetic energy of

100 J

a woman who normally weighs 400 N stands on top of a very tall ladder so she is one earth radius above earths surface. what is her weight there?

100 N

what is the mass of a ball moving at 4 m/s with a momentum of 48 kg m/s

12 kg

what is the speed of a 6-kg ball with a momentum of 72 kg m/s

12 m/s

what is the mass of a ball moving at 3 m/s with a momentum of 48 kg m/s

16 kg

a car moves 4 times as fast as another identical car. compared with the slower car, the faster car has

16 times the kinetic energy

a shopping cart moves with a kinetic energy of 40 J. if it moves at twice the speed, its kinetic energy is

160 J

a car moving at 50 km/h skids 20 m with locked brakes. how far will it skid if its initial speed is 150 km/h?

180 m

If you exert 100 J to lift a box in 50 s your power output is

2 W

a 2 kg mass that weighs 20 N has 40 J of potential energy relative to the ground. what is its height?

2 m

When the input piston of a hydraulic press is depressed 20 cm, the output piston is observed to move 1 cm. An input force of 1 N can raise no more than

20 N

a 1000-kg truck moving at 10 m/s that brakes to a stop in 5 s has an average braking force of

2000 N

If you exert 6 N across a distance of 2 m in 3 s you'll deliver a power of

4 W

A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy that is

40 J

Phil stands at rest with both feet on a scale that reads 500 N. When he gently lifts one foot, the scale reads

500 N

what is the force of gravity on a 500 N woman standing on earths surface?

500 N

When Danny Diver who weighs 500 N steps off a diving board 10 m above the water, he hits the water with kinetic energy of

5000 J

the planet juptiter is about 300 times as massive as earth, yet on its surface you would weigh only about 3 times as much because

Jupiter's radius is 10 times Earth's radius

a massive ram of a pile driver falling from rest strikes a pile with a speed that depends on the

all of the above - initial height and potential energy of the ram, and distance the ram falls

a car traveling along the highway brakes to a stop. a greater braking force is required when the car has

all of the above - less stopping distance, more momentum, more mass

You can experience weight

all of the above - in an accelerating elevator away from earth, standing on earths surface, and in a rotating habitat in space

a circus diver drops from a high pole into water far below. when he is halfway down

all of the above- he has gained the same amount of kinetic energy as half his initial potential anergy, his kinetic and potential energies are equal, his potential anergy is halved

if your mass doubles, your weight

also doubles

When you simultaneously drop a light tennis ball and a heavy bowling ball, they hit the floor

at the same speed

if a monkey floating in outer space throws his hat away, the hat and the monkey will both move

away from each other but at different speeds

whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is

both the same with the haystack and the brick wall

a very massive object A and a less massive object B move toward each other under the influence of gravity. which force, if either, is greater?

both forces on each other are the same

Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter

both of these - increased time of contact and decreased contact force

one second after a ball rolls off the edge of a horizontal surface at the speed of 10 m/s,

both of these - its vertical component of velocity is 10 m/s and its speed is about 14 m/s

Which requires more work: lifting a 50-kg sack vertically 2 meters or lifting a 25-kg sack vertically 4 meters?

both require the same amount of work

while driving down the highway a lovebug splatters onto your windshield. which experiences the greater force of impact?

both the same but with difference consequences

a karate chop is more effective if one's hand

bounces upon impact

If Earth's mass decreased to one-half its original mass with no change in radius, then your weight would

decrease to one-half

An open freight car rolls friction free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, the car's speed

decreases

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, the speed of the skateboard

decreases

when bullets are fired in a forward direction from a fighter aircraft, the momentum of the aircraft

decreases

which has the greater momentum when moving? a container ship or a bullt?

either depending on speed

the force of air impact upon the sail of a boat is greater if the air

encounters the sail head on

A popular swinging-balls apparatus (Newton's cradle) consists of a series of identical elastic balls suspended by strings so they barely touch each other. When two balls are pulled away from one end and released, they strike the row of balls and two balls pop out from the other end. If instead, one ball popped out with twice the speed, this would be a violation of conservation of

energy

When Jean standing on slippery ice catches her leaping dog Daisy, the momentum of both Jean and Daisy after the catch is

equal to their combined momentum before the catch

the force that accelerates a rocket in outer space is exerted on the rocket by the

exhaust gasses

Two identical arrows, one with twice the speed of the other, are fired into a bale of hay. the faster arrow will penetrate the bale

four times as far as the slower arrows

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, he doesn't slip off the skateboard because of

friction between his feet and the board

a straw is used for a pea shooter. when you blow through the straw the speed of the emerging pea will be greater if the straw is

full length

a heavy truck and a small car roll down a hill at the same speed and need to stop int eh same amount of time. compared with the force to stop the car, the force needed to stop the truck is

greater

When an apple falls to the ground, momentum is transferred to the ground. The momentum absorbed by the ground is

greater if the apple bounces

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is

greater with the brick wall

When a bus brakes to a stop its kinetic energy transforms to

heat

the speed of a bullet fired from a gun will be about the same speed as the speed of the recoiling gun

if the masses of the bullet and the gun are equal

jogging Jake runs along the top of a moving flatcar in the direction of motion of the flatcar. If he runs in the opposite direction, the combined momentum of Jake and the flatcar relative to an observer at rest will be

less

a ball is projected into the air with 900 J of kinetic energy that is transformed to potential energy at the top of its trajectory. when it returns to its original level after encountering air resistance, its kinetic energy is

less than 900 J

according to Newton, the greater the distance between gravitationally interacting objects, the

less the gravitational force between them

When you can't escape being hit by a fast-moving object, you'll suffer a smaller force if the collision time is

long

compare with falling on a wooden floor, a wine glass may not break when it calls on a carpeted floor because of

longer time to stop

An iron ball and wooden ball of the same size are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater

momentum

an object in motion is an object that has

momentum

you throw a golf ball at a massive bowling ball at rest and the golf ball bounces backward from it. after the bounce, compared with the golf ball, the bowling ball has more

momentum, but less kinetic energy

why doesn't the moon fall toward the earth like apples do?

moon does fall but due to tangential motion it also falls around earth

A fan attached to an ice sailcraft stalled on a windless day blows air into the sail that bounces backward upon impact. The boat

moves in the direction of the wind impact force

If you push an object twice as far while applying the same force, you do

twice as much work

When you push an object a certain distance while applying twice the force, you do

twice as much work

a 1000 kg car and a 2000 kg car are hoisted the same vertical distance in a service station. raising the more massive car requires

twice as much work

When you ride your scooter you have momentum. When you ride twice as fast you have

twice the momentum

Dwarf planet Pluto was discovered by perturbations of

uranus and neptune

compared to other fundamental forces, the Universal Gravitational Constant (G) indicates gravity to be a relatively

weak force

Passengers in a high-flying jumbo jet feel their normal weight in flight, while passengers in the orbiting space shuttle do not. This is because passengers in the space shuttle are

without support forces