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
