. The 50-kg crate is pulled by the constant force P. If the crate P starts from rest and achieves a speed of 10 m/s in 5 s, determine the magnitude of P. The coefficient of kinetic friction between the crate and the ground is µk = 0.2.

Explanation:

Let assume that crate moves out on a horizontal ground and experiments a constant acceleration. Equations of equilbrium are created by applying Newton's Laws (assumed that movement goes in the positive direction)

The acceleration experimented by the crate is:

By making some algebraic manipulations over equations of equilibrium, an expression for pulling force P is derived:

whichever one it is, it's definitely not one that you included on the list you provided.

hypothesising or postulating