Question

1. Two crates, A and B, sit at rest side by side on a frictionless horizontal surface. The crates have masses mA and mB. A horizontal force is applied to crate A and the two crates move off to the right. (a) Draw clearly labelled free-body diagrams for crate A and for crate B. Indicate which pairs of forces, if any, are third-law action-reaction pairs. (b) If the magnitude of force is less than the total weight of the two crates, will it cause the crates to move? Explain.

Answer 1

(a)

$m_Ag=N_A, m_Bg=N_B, F=N_{B}^{'}.$

(b)

If the friction is low, crates can be moved.