Question

6 a pencil is stationary on a desk. which of the following best explains the force(s) acting on the pencil? a gravity is pulling down on the pencil, but it is not strong enough to pull the pencil to the floor b the desk is blocking the pencil from falling to the floor, and air pressure is pushing down on the pencil c gravity is pulling down on the pencil, and the desk is pushing up on the pencil d there are no forces acting on the pencil, so the net force on it is zero

Explanation:

• Option A: Gravity's strength isn't the reason the pencil doesn't fall; balanced forces are. So A is wrong.
• Option B: The desk pushes up (normal force), not block, and air pressure isn't a main factor here. B is wrong.
• Option C: For a stationary object, gravity (downward) and normal force from the desk (upward) are equal and opposite, balancing each other. This matches Newton's first law for equilibrium.
• Option D: Forces (gravity and normal force) do act on the pencil, so D is wrong.

Answer:

C. Gravity is pulling down on the pencil, and the desk is pushing up on the pencil