Question

A car of mass 550 kg is moving at a speed of 1.5 m/s. A man pushes the car, increasing the speed to 3.2 m/s. How much work did the man do?

Answer 1

Work is 'energy'

Assuming that we ignore any losses, and assuming the ground is level, then the work he did went into increasing the car's KINETIC energy

The formula to work out KE is

\[KE = \frac{ mv ^{2} }{2 }\]

So work out the KE at the beginning, AND at the end - and the difference Is the work done by the pusherman

Answer 2

Work=difference of kinetic energy

Answer 3

Initial kinetic energy=.5mu^2=.5*550*1.5^2

Answer 4

Final kinetic energy=.5mv^2=.5*550*3.2^2