PHYSICAL SCIENCE 101 TEST#2-Spr Semester '03

An object is propelled along a straight-line by a force. If the net force were doubled, its acceleration would

Your answer:
stay the same.
double.
none of these.
quadruple.
halve.

A 10-N falling object encounters 10 N of air resistance. The net force on the object is

Your answer:
4 N.
6 N.
10 N.
none of these.
0 N.

A feather and a coin dropped in a vacuum fall with equal

Your answer:
momenta.
forces.
kinetic energies.
accelerations.
none of these

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

Your answer:
both of these.
none of these.
kinetic energy.
momentum.

The ground speed of an airplane that has an airspeed of 100 km/h when it is in a 100-km/h crosswind is

Your answer:
0 km/h.
150 km/h.
100 km/h.
141 km/h.
200 km/h

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

Your answer:
trace a curve that matches the Earth's curvature.
all of these
none of these.
accelerate downward at g as it moves horizontally.
return later to its starting position and repeat its falling behavior.

Consider an escalator at an angle of 45 degrees above the horizontal that moves with a velocity of 2.0 m/s. The vertical component of its velocity is about

Your answer:
1.4 m/s.
none of these.
1.6 m/s
2.0 m/s.
0.7 m/s.

A 5000-kg freight car runs 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 Car?

Your answer:
6 m/s
4 m/s
8 m/s
5 m/s
none of these.

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 stick together, and move at a speed of

Your answer:
8 m/s.
6 m/s.
none of these.
3 m/s.
4 m/s.

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

Your answer:
3000 N.
1000 N.
2000 N.
4000 N.
5000 N.

Two projectiles are fired at equal speeds but different angles. One is fired at an angle of 30 degrees and the other at 60 degrees. The projectile to hit the ground first will be the one fired at(neglect air resistance)

Your answer:
60 degrees.
30 degrees.
both hit at the same time.

A bullet fired horizontially hits the ground in 0.5 s. If it had been fired with twice the speed in the same direction, it would have hit the ground in

Your answer:
less than 0.5 s.
more than 0.5 s.
0.5 s.

Strictly speaking, if any electrical device in your car is turned on(such as an air conditioner, headlights, or even a radio), more gasoline is burned by the engine. This statement is

Your answer:
none of these.
totally false.
true only if the car's engine is running.
true ony if the car's engine is stopped.
always true.

In the vacuum of outer space, there is no

Your answer:
gravity.
atmospheric pressure.
both of these

A "weightless" astronaut in an orbiting shuttle is

Your answer:
like the shuttle, pulled by the Earth's gravitation.
none of these
shielded fron the Earth's gravitational field.
pulled only by gravitation to the shuttle which cancels the Earth's gravitational pull.
beyond the pull of gravity.

A lunar month is about 28 days. If the Moon were farther from the Earth than it is now, The lunar month would be

Your answer:
more than 28 days.
about 28 days.
less than 28 days.

A projectile is fired vertically from the surface of the Earth at 10 km/s. The projectile will

Your answer:
rise and fall back to Earth's surface.
none of these.
go into elliptical orbit about the Earth.
go into circular orbit about the Earth.

Consider a monkey wrench released at rest at the far edge of the solar system. Suppose that it drops to the Earth by virtue of only Earth's gravity. It will strike Earth's surface with a speed of about

Your answer:
11 km/s
9.8 m/s.
the speed of light.
8 km/s.

A rocket fired vertically at 11.2 km/s will escape the Earth. If it is instead fired horizontally at this speed, free from obstructions, will it still escape the Earth?

Your answer:
yes
there's no way to tell
no

What prevents satellites such as the space shuttle from falling?

Your answer:
centrifugal force
gravity
centripetal force
the absence of air drag
Nothing, they continually fall around the Earth.

The average momentum of a 70-kg runner who covers 400 m in 50 s is

Your answer:
57 kg·m/s.
none of these
560 kg·m/s.
8.75 kg·m/s.
5490 kg·m/s.

A boxer punches a sheet of paper in midair and brings it from rest up to a speed of 40 m/s in 0.05 s. If the mass of the paper is 0.01 kg, the force of impact on the paper is about

Your answer:
none of these
0.08 N.
8.0 N.
80 N.
0.8 N.

A projectile is thrown into the air at an angle of 50 degrees and lands on a target that is at the same level the projectile started. It will also land on the target if it is thrown at an angle of

Your answer:
45 degrees.
40 degrees.
55 degrees.
60 degrees.
none of these.

The reason 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

Your answer:
time.
distance.
both of these.
neither of these.

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

Your answer:
doesn't change.
increases.
decreases.