Question

A car and a truck moving with the same k.e. on the same road. their engines are simultaneously switched off. which one will stop at a smaller distance?

Answer 1

Let the mass of the car = m and mass of the truck = M

Let the velocities of the car and truck is v and V respectively. 

Given the kinetic energy of car = kinetic energy of truck 

Or,

½ mv^2 = ½ MV^2 or, mv^2 = MV^2 

Since M>m, therefore v>V. 

Also, Normal force on truck is greater than the car so is the friction force. 

Thus, the truck will stop in lesser distance.