Compare the kinetic and potential energies of a 400 kg box being moved horizontally by a forklift at a speed of 5 m/s. The box is at a height of 1 m.

Question

Compare the kinetic and potential energies of a 400 kg box being moved horizontally by a forklift at a speed of 5 m/s. The box is at a height of 1 m.

Answer 1

The potential energy stays constant because the height is not changing.  Potential energy = mgh, where m is the mass (400 kg), g is the acceleration due to gravity (9.8 m / sec²), and h is the height (1 m).  So the result is 400 * 9.8 * 1 = 3920 J

 

The kinetic energy = 1/2 mv² = 0.5  * 400 kg * (5 m/sec)² = 5000 J.  It also stays constant because the speed is not changing.

 

So the kinetic energy is greater than the potential energy.