Question 7 (3 points) (3.08_Q7) There are 2 properties of objects which combine to create a stable orbit of one object around the other. One of the properties is the graviational force between the 2 objects. The other vital property for a stable orbit is .

Question 7 options:

the electromagnetic force between the 2 objects.

the density of the smaller object.

the volume of the smaller object.

the velocity of the object in the orbital path.

Question 8 (3 points)
(3.08_Q8) Which force causes a decrease in velocity (a negative acceleration)?

Question 8 options:

gravitational force

strong nuclear force

weak nuclear force

friction force

Question 9 (3 points)
(3.08_Q9) What happens to an object's gravitational pull if it's mass is increased?

Question 9 options:

it increases

it stays the same

it decreases

Question 10 (3 points)
(3.08_Q10) Earth's gravity helps create the acceleration which bends the path of the Moon to create a stable orbit. What does the Moon's gravity do?

Question 10 options:

The Moon's gravity pulls back on the Earth with the same force the Earth pulls on the Moon.

The Moon's gravity pushes the Earth away from the Moon so an orbit is created.

The Moon's gravity can only pull on smaller objects, like asteroids, and has no effect on Earth.

The Moon's gravity doesn't effect anything. That's why the Moon has no atmosphere.

Question 11 (3 points)
(3.08_Q11) What is the difference in "free fall" to a scientist and to a skydiver?

Question 11 options:

There is no difference. Both scientists and skydivers consider being pulled by gravity thru the air is free fall.

To a scientist, gravity is the only force acting on the object. To a skydiver, the entire time they are free falling thru the air until they deploy their parachute.

Skydivers considers themselves to be in free fall if they are traveling less than 50 miles per hour.

Question 12 (3 points)
(3.08_Q12) F=ma, the acceleration from Earth gravity is 9.8 m/s/s. What is the force of gravity on a 123 kg lead ball.

Question 12 options:

0.0797 Newtons

12.6 Newtons

1210 Newtons

Question 13 (3 points)
(3.08_Q13) F=ma, Earth gravity causes an acceleration of 9.8 m/s/s

A 10.0 kg ball of ice is dropped from 3 meters. What is the gravitational force pulling it downward?

Question 13 options:

98.0 N

0.98 N

1.02 N

Question 14 (3 points)
(3.08_Q14) Because of density differences, the 10.0 kg ball of ice and the 123 kg ball of lead have the same size. When both are dropped from 3.0 meters, they hit the ground at the same instant. The 123 kg ball of lead is pulled by gravity with 12.3 times more force thant the 10.0 kg ball of ice. Why doesn't the extra force created by the extra mass cause the lead ball to hit the ground first?

Question 14 options:

This is rubbish, of course the lead ball hits the ground first.

The air resistance is proportional to the mass, so the air slows down the lead ball more than the ice ball.

The lead ball has 12.3 times more force pulling on it, but it also has 12.3 times more inertia resisting that force. So they fall at the same rate.