Exam 2: Physics

A huge rotating cloud of particles in space gravitate together to form an increasingly dense ball. As it shrinks in size, the cloud

rotates faster.

For a system in mechanical equilibrium

the resultant forces and torques must both be zero.

A carnival has a Ferris wheel where the seats are located halfway between the center and outside rim. If you were at the outside rim, your angular speed while riding on this Ferris wheel would be

the same and your tangential speed less.

Rockets that launch satellites into orbit need less thrust when fired from

Hawaii.

The origin of any micro tides in the human body is most likely the

Earth

If all people, animals, trains and trucks all over the world began to walk or run towards the east, then the

Earth would spin a bit slower.

If a turntable's rotational speed is doubled, then the linear speed of a pet hamster sitting on the edge of the record will

double

A 1-N apple falls to the ground. The apple hits the ground with an impact force of about

not enough information given to say

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 information, what is the mass of the meter stick?

1 kg

A bungee jumper attains a speed of 30 m/s just as the bungee cord begins to stretch. If the period of stretch is 2 s, the magnitude of the jumper's average deceleration is about

1.5 g.

Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide and stick. The combined mass moves at

1/2 m/s.

A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at

1/3 m/s.

A gun with a muzzle velocity of 100 m/s is fired horizontally from a tower. Neglecting air resistance, how far downrange will the bullet be 1 second later?

100

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?

100 N

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

2 m/s.

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

2 m/s.

Suppose you're on a Ferris wheel at a carnival, seated 10 m from the Ferris wheel's axis. If you make a complete rotation each minute, your linear speed is

62.8 m/min.

A car's engine is 20% efficient. When cruising, the car encounters an average retarding force of 1000 N. If the energy content of gasoline is 40 megajoules per liter, how many kilometers per liter does the car get?

8

The concept of force is not fundamental to

Einstein's theory of gravitation.

All places on the Earth would have high tides at the same instant if the

None of the above choices are correct.

The amount of gravitational force that acts on the space shuttle while in orbit is

almost as much as the shuttle's weight on the Earth's surface.

When a rifle is fired, it recoils as the bullet is set in motion. The rifle and bullet ideally acquire equal

but opposite amounts of momentum.

According to Kepler's laws, the paths of planets about the sun are

ellipses

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

four times further than the slower arrow.

If the radius of the Earth somehow decreased with no change in mass, your weight would

increase.

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

increases

A bullet has more kinetic energy than the recoiling rifle from which it is fired is because the force on the bullet acts over a

longer distance.

If the speed of a moving object doubles, which of the following also doubles?

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

A golf ball moving forward with 1 unit of momentum strikes and bounces backward off a heavy bowling ball that is initially at rest and free to move. The bowling ball is set in motion with a momentum of

more than 1 unit.

A 1-kg ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about

more than 2.0 J.

Minimal orbit speed about the Earth is about 8 km/s. Minimal orbital speed about Jupiter would be

more than 8 km/s.

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.

An object that has kinetic energy must be

moving

A hollow spherical planet is inhabited by people who live inside it, where the gravitational field is zero. When a very massive space ship lands on the planet's surface, inhabitants find that the gravitational field inside the planet is

non-zero, directed toward the spaceship.

A river 100 m wide flows due south at 1 m/s. A boat that goes 1 m/s relative to the water leaves the west bank. To land at a point due east of its starting point, the boat must be pointed

nowhere—it can't be done.

Which moves faster in m/s on a merry-go-round: a horse on the inside or a horse on the outside near the outer rail?

outside horse

A rocket coasts in an elliptical orbit about the Earth. To attain escape velocity using the least amount of fuel in a brief firing time, should it fire off at the apogee, or at the perigee? (Hint: Let "Fd = change in KE" guide your thinking.)

perigee, where it is closest and fastest

When a star collapses to form a black hole, its mass

remains the same.

A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air drag, its horizontal component of velocity

remains unchanged.

Without air resistance, a projectile fired horizontally at 8 km/s from atop a mountain would

return later to its starting position and repeat its falling behavior. trace a curve that matches the earth's curvature. accelerate downward at g as it moves horizontally.

A projectile is fired vertically from the surface of the Earth at 5 km/s. The projectile will

rise and fall back to the Earth's surface.

The Earth is currently accelerating toward the sun (centripetal acceleration). If the sun collapsed into a black hole, this acceleration would

stay the same.

It is correct to say that impulse is equal to

the change in momentum it produces.

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

the top

The speeds of the planets about the sun depend on

their distances from the sun.

If you push an object a given distance, while applying twice the force, you do

twice as much work.

An object lifted 10 meters gains 200 J of potential energy. If the same object is lifted 20 meters, its potential energy gain is

twice as much.

A flywheel's mass is twice that of another of the same size and shape. The more massive flywheel's rotational inertia is

two times the other's.

Half way to the center of a completely hollow planet with a thin uniform shell, your weight would be

zero.