Question

A 12 n cart is moving on a horizontal surface with a coefficient of kinetic friction of 0.20. what force of friction must be overcome to keep the object moving at a constant velocity?

Answer 1

We must remember that the total net force equation at constant velocity is:

F – Ff = 0

of

F - µN = 0

Using Newton's 2nd Law of Motion:

F = m a 

Where,

F = net force acting on the body 
m = mass of the body 
a = acceleration of the body 

Since the cart is moving at a constant velocity, then acceleration is zero, hence the working equation simplifies to 

F = net Force = 0 

Therefore, 

F - µN = 0 

where 

µ = coefficient of friction = 0.20 
N = normal force acting on the cart = 12 N 

Therefore, 

F - 0.20(12) = 0 

F = 2.4 N