# What are the forces acting on an object?

## Homework Statement

In the attached file file.

None

## The Attempt at a Solution

In both cases Earth’s gravitational force always acts. For the sled, there is a force opposing the motion which can both be the frictional force between the sled and the hill and air resistance. Answer is E for the left side question. For the ball, there is air resistance. But I am not sure about the terms uses ,”frictional for of the air” “retarding force due to the mass of the ball”. Also, I don’t know if the ball’s mass intrigues its motion.

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Chestermiller
Mentor
There is no actual retarding force due to the mass of the ball. However, if the ball is accelerating downward, the gravitational force exceeds the air resistance force by the mass of the ball times its acceleration.

There is no actual retarding force due to the mass of the ball. However, if the ball is accelerating downward, the gravitational force exceeds the air resistance force by the mass of the ball times its acceleration.
Ah, understood. So, it’s E for the left side question and C for the other one?

• Chestermiller