. 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:

d.7.5cm is your answer

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it