Question

When a horizontal force P acts on a cart of mass 20 kg,it moves with a uniform velocity on a horizontal floor. When a force of 1.2P acts on the cart, it moves with an acceleration of 0.05 metre per second square. Find the value of P.

Answer 1

mass = 20kg
friction = P
force = 1.2 P
a = 0.05 m/s^2

1.2P - P = 20 * 0.05
0.2P = 1
P = 1/0.2
P = 5N

Answer 2

When force P acts and the cart travels with uniform velocity (0 acceleration), it means that force P cancels the Friction force acting in the opposite direction.

  net force on cart = mass * acceleration
   1.2 P - friction = mass * acceleration
     1.2 P - P = 20 kg * 0.05 m/sec/sec
       0.20 P = 1  Newton

           P = 5 Newtons