Question

A body ,having kinetic energy k,moving on a rough horizontal surface ,is stopped in a distance x.the force of friction on the body is (a) K/X (b)√k/x (c)k/√x (d) k

Answer 1

• We are given that the body has kinetic energy k and stops at a distance x.
• We have to find the force of friction on the body.
• Let m be the mass, v be initial velocity of the body, F be frictional force and x is given as distance after which it stops.
• According to work energy theorem,

       F * x = 1/2 * m * v^2

• Where 1/2 * m * v^2 is equal to k, the kinetic energy of the body
• So, we get equation as

       F * x = k

       F = k / x

• ANS : So the force of friction on the body is K / X.