Question

A horizontal force of 90.0 N is required to push a 75kg object along a horizontal surface at a constant speed. What is the magnitude of the force of friction. Please show your work I am having troubles.

Answer 1

If the object is moving at a constant speed, acceleration is 0. So:

$F = ma F = m\times 0 F = 0$

The resultant force is 0. So the force pushing the object must be equal to the friction force acting, so 

Friction = 90 N