Question

A body of mass 5kg has momentum of 10kg m/s.when a force of 0.2N is applied on it for 10 s, what is the change in its kinetic energy

Answer 1

mass = 5 kg
momentum ( mass * velocity ) = 10 kg m /s
force = 0.2 N
time = 10 s

momentum ( mass * velocity ) = 10 kg m /s
velocity = 10 ÷ mass
velocity = 10 ÷ 5
velocity = 2 m /s
change in kinetic energy = final kinetic energy - initial kinetic energy
displacement = velocity * time
displacement = 2 * 10 = 20 m

change in kinetic energy = final kinetic energy - initial kinetic energy
change in kinetic energy = (force * displacement ) _ 1/2 m * velocity * velocity

change in kinetic energy = (0.2 * 20 ) - 10

change in kinetic energy = 4 -10

=-6