Question

A $60.0-kg$ person running at an initial speed of $4.00m/s$ jumps onto a $120-kg$ cart initially at rest (Fig. $P9.69$). The person slides on the cart’s top surface and finally comes to rest relative to the cart. The coefficient of kinetic friction between the person and the cart is $0.400$. Friction between the cart and ground can be ignored.
Find the friction force acting on the person while he is sliding across the top surface of the cart.

Answer 1

Given,

mass of person is $60kg$

initial velocity is $4m/s$

mass of cart is $120kg$

Co-efficient of kinetic friction is $0.4$

We know that friction force is

$F_k=\mu N$

In any object weight $\left(mg\right)$ always balance the normal force therefore we can replace normal force by weight.

$F_k=\mu mg$

Substitute all value in above equation

$F_k=0.4\times 60\times 9.8F_k=235.2N$

Hence, friction force acting on the person while he is sliding across the top surface of the cart is $235.2N$