Question

identifying forces acting on a falling object
an apple is falling from a tree. disregarding air resistance, which diagram shows the free - body diagram of the force or forces acting on the apple?

Explanation:

Step1: Recall free - body diagram rules

A free - body diagram shows the forces acting on an object. When an apple is falling from a tree and we disregard air resistance, the only force acting on it is the gravitational force ($F_g$) which acts downwards towards the center of the Earth. There is no normal force ($F_N$) because the apple is not in contact with a surface, and no other horizontal or additional vertical forces (like a pushing force $F_p$) are acting on it.

Step2: Analyze each diagram

• First diagram: Shows a normal force ($F_N$) upwards and gravitational force ($F_g$) downwards. But since the apple is falling (not in contact with a surface), there is no normal force. So this is incorrect.
• Second diagram: Shows only the gravitational force ($F_g$) acting downwards. This is consistent with our analysis as the only force acting on the falling apple (without air resistance) is gravity.
• Third diagram: Shows a horizontal gravitational force, which is incorrect as gravity acts vertically downwards.
• Fourth diagram: Shows a downward gravitational force and a horizontal pushing force. There is no pushing force acting on a freely falling apple (disregarding air resistance), so this is incorrect.

Answer:

The second diagram (the one with only $\boldsymbol{F_g}$ acting downwards)