A person standing on top of a 40-m high cliff throws a rock with a mass of 0.25 kg off the cliff.The rock leaves the person's hand with a speed of 14 m/s and makes an angle of 60 degrees above the horizontal.What is the kinetic of the rock when it reaches the top of its path?

Question

Quizplus · Accepted Answer

At the top of its path, the vertical component of the velocity is 0, so only the horizontal component contributes to kinetic energy. The horizontal velocity is 14 * cos(60°) = 7 m/s. Kinetic energy = 0.5 * 0.25 kg * (7 m/s)^2 = 6.125 J, approximately 6.1 J.

A Person Standing on Top of a 40-M High Cliff