Question

which free body diagram best shows the forces acting on the box when the cart is pushing it forward (time 3)? (blue vector is force from cart, red vector is force of friction, and green vector is force of air resistance.)

Explanation:

When the cart is pushing the box forward, the force from the cart (blue vector) acts in the forward direction. Friction (red vector) and air resistance (green vector) act in the opposite direction (against the motion). In option A, the blue vector (force from cart) is forward, red (friction) and green (air - resistance) are backward. In option B, the blue vector is backward which is incorrect. In option C, there is no air - resistance vector. In option D, the directions of vectors are jumbled.

Answer:

A.