Question:

I am working on my astrophysics homework and I am completely lost.Is there anyone who can help me with the following questions? I am a new student. Thanks

 

1.Consider a large truck and a small car driving up a straight, steep hill. The truck is moving at 60 miles per hour and the car at 30 miles per hour. Assuming that the speeds are constant, which of the two vehicles experiences a larger net force?

the truck

the car

the same: zero net force

2

When an astronaut experiences weightlessness in space, their mass is

zero.

the same as on the Earth.

double than on the Earth.

becoming lesser and lesser as s/he is going higher.

3

An astronaut in orbit around the Earth drops her pen, and it floats gently next to her hand. Why does it not fall to the floor?

There is no gravity in space.

The gravitational pull is very weak at typical altitudes for orbiting spacecraft.

Objects in orbit have no mass.

All objects in the spacecraft are falling toward the Earth at the same rate.

The net force on the pen is zero.

4

A weather satellite moves at a constant orbital speed around the Earth. Is this satellite accelerating?

Yes, the satellite is accelerating — its speed is constant but its direction is changing.

Yes, the satellite is accelerating — the force of gravity is pulling it toward the ground.

Yes, the satellite is accelerating — it is in freefall toward the ground.

Yes, the satellite is accelerating — its speed is constant but its direction is changing and Yes, the satellite is accelerating — it is in freefall toward the ground..

Yes, the satellite is accelerating — its speed is constant but its direction is changing, Yes, the satellite is accelerating — the force of gravity is pulling it toward the ground and Yes, the satellite is accelerating — it is in freefall toward the ground. are correct.

5

The Moon is gravitationally attracted to the Earth. Is the Earth gravitationally attracted to the Moon?

Yes, but the force of attraction is less.

Yes, and the force of attraction is the same.

Yes, but the force of attraction is greater.

No, the Moon has no gravity.

6

A rocket in space fires its engines continuously until it runs out of fuel. Describe the motion of the rocket.

The rocket's speed increases until its engines stop firing, and then coasts in a straight line.

The rocket's speed is a constant value until the engines stop firing, and then coasts to a stop.

The rocket's speed increases until its engines stop firing, and then coasts to a stop.

The rocket's speed does not change, and it continues to move in a straight line.

The rocket does not move, as the engines have nothing to push against.

7

Which of the following objects is experiencing the Earth's gravitational force?

a boat floating in water

an airplane taking-off

a skydiver falling under the force of gravity

all of these choices are correct

Only an airplane taking-off and a skydiver falling under the force of gravity above.

8

The escape velocity from the Moon is 2.4 km/s. If an astronaut hits a golf ball such that it just reaches this speed, the ball will __________________________.

continue moving away from the Moon, never to return

follow a very elliptical orbit around the Moon

move away from the Moon, but return some time later

either orbit the Moon or escape its gravitational pull, depending on the direction the ball is hit