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

The horizontal floor has a frictional force F that inhibits the movement of the cart.

Acceleration of cart = P - F = 0 as the cart moves with constant velocity and acceleration is 0
                   So F = P

When a force of 1.2 P acts on the cart, acceleration a of the cart is
                1.2 P - F = m a
               1.2 P - P = 20kg * 0.05 m/sec²

                P = 1/0.2 = 5 Newtons

Answer 2

Given :-

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.

Solution :-

• Since in the first case the body moves with a uniform velocity , the resultant force on it in the horizontal direction must be zero .

H + force of friction = 0

or , force of friction = -H.

• In the second case , the net horizontal force is ( 1.5 H - H ) = 0.5H.

Applying Newton's second law ,

→ F = ma

→ 0.5 H = 50 kg × 0.1 m/s²

→ H = ( 50 kg × 0.1 m/s² ) / 0.5 = 10 N .

Thank You !