Question

When a horizontal force P acts on a cart of mass 20 kg it moves with a constant velocity. When the force of 1.2 P acts on the same cart it moves with an acceleration of 0.05 m/$s^2$ to find the value of P.

Answer 1

Step 1, Given data

mass of the cart = 20 kg

Force = P Acceleration = 0

Force = 1.2 P Acceleration = 0.05 m/$s^2$

Step 2, Finding the value of P

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

In case 1 the acceleration of the cart is zero which means that the P is equal to the frictional force F

So F = P
In case 2
When a force of 1.2 P acts on the cart, the acceleration a of the cart is 0.05 m/$s^2$

So we can write

$1.2P-F=ma$

$Or,1.2P-P=20\times 0.05$

$Or,0.2P=1$

$Or,P=5N$

Hence the value of P is 5 Newton.