kinetic energy of moving object

Question

The kinetic energy of a moving object is KE = 1/2 mv², where m is the mass and v is the speed. An average apple has a mass of 0.19 kg. How fast must the apple travel in m/s to have kinetic energy of 0.68 million joules?

Answer 1

K = mv² /2 ⇒

v = √(2K / m)

Plug in the numbers

m = 0.19 kg

K = 680,000 joules

and get v in units of meters per second.