Physics 1310 Exam 2 - gregory spencer

Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?

0

A 1-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, what is the mass of the meter stick?

1 kg

A weight watcher who normally weights 400 N stands on top of a very tall ladder so she is 1 earth radius about the Earth's surface. How much would she weigh there?

100 N

Two identical 5000-kg bulldozers roll toward each other on a level road without friction (one at 1 the other at 2). Just before they collide, one has a kinetic energy of 2500 J and the other 10,000 J, At this instant their total kinetic energy is

12,500 J

A ball is moving at 3 m/s and has momentum of 48 kg m/s. What is the ball's mass?

16 kg

A car moves 4X as fast as another identical car. Compared to the slower car, the faster car has

16X the Kinetic Energy

Suppose the circumference of a bicycle wheel is 2m. If it rotates at 1 revolution/sec when you are riding, then your speed will be

2 m/s

A 5000-kg freight car moving at 2 m/s runs into a 10,000-kg freight car at rest. They couple upon collision an move away as one body at

2/3 m/s

A 1000-kg car moving at 10 m/s breaks to a stop in 5 seconds. The average breaking force is

2000 N

An asteroid exerts 360 N gravitational force on a nearby spacecraft. If the spacecraft moves to a position 3X as far from the center of asteroid, the force will be

40 N

A car that travels 2X as fast as another when braking to a stop will skid

4X as far

A 2-kg mass is held 4 m above the ground. What is the gravitational potential energy of the mass with respect to ground?

80 J

A coin and a ring, each with the same mass and radius, roll down an incline starting at the same time. The one to reach the bottom 1st will be

Both will reach is at the same time

A supplier wants to make a profit by buying metal by weight at one altitude and selling it at the same price per pound at another altitude. The supplier should

Buy at high altitude and sell at low altitude

An object is placed exactly halfway between Earth and Moon. The object will fall toward the

Earth

The impulse momentum relationship is a direct result of

Newton's 2nd law

The conservation of momentum is most closely related to

Newton's 3rd law

When an object is in motion, which could NOT have a value of zero?

None: not kinetic energy, mass, inertia, or momentum

NASA launches most of its satellites and all of its manned missions from

The Kennedy Space Station in Brevard County, Florida

When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time of the impact about 10 times as great as for stiff legged landing. In this way the average force your body is experiencing is

about 1/10 as great

The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is

above a place of support

inside a freely falling elevator, there would be no

apparent weight for you

A car travels in a circle with constant speed. The net force on the car is

directed towards the center of the curve

According to Newton, doubling the distance between two interacting objects

divides by 4 the gravitational force between them

How far must one travel to get away from the Earth's gravitational field?

forget it, you can't travel far enough

When a car is braked to stop, its kinetic energy is transformed to

heat

A bullet is fired from a gun. The speed of the bullet will be about the same as the speed of the recoiling gun

if the mass of the bullet=mass of gun

If the Earth rotated more slowly on its axis, your apparent weight would

increase

Two objects more toward each other because of gravity. As the objects get closer and closer, the acceleration of each

increases

When a twirling ice skater brings her arms inward, her rotational speed

increases

If an object has kinetic energy, then it also must have

momentum

Two objects have the same size and shape, but one is much heavier than the other. When they are dropped simultaneously from a tower, they reach the ground at the same time, but the heavier one has a greater

momentum

Suppose you are at the center of a large freely rotating horizontal turntable. As you crawl from the center towards the edge, the angular momentum of you and the turntable

remains the same, but RPMs decrease

A torque acting on an object tends to produce

rotation

It is correct to say that impulse is equal to

the change in momentum it produces

Two identical freight cars roll without friction (one at 1 m/s the other at 2 m/s) toward each other on a level track. They collide, couple together, and roll away in at the direction that

the faster car was initially going

For a system in mechanical equilibrium

the resultant forces and torques must both be 0

Consider two planets in space that gravitationally attract each other. If the masses of both planets are doubled, and the distance between them is also doubled, then the force between them is

the same

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

the same as the potential

If you find that twice as much work is needed to perform a task but it takes twice as much time, the amount of power needed is

unchanged