A 2.0-kg mass is projected from the edge of the top of a 20-m tall building with a velocity of 24 m/s at some unknown angle above the horizontal. Disregard air resistance and assume the ground is level. What is the kinetic energy of the mass just before it strikes the ground?

968 J

Explanation:

The computation of the kinetic energy is shown below:

Given that

mass m = 2 kg

height h = 20 m

velocity v = 24 m / s

Now

According to the law of conservation of energy ,

= K.E at top + P.E at top

= ( 1 ÷ 2) mv ^ 2 + mgh

= 576 + 392

= 968 J

wavelength divides in half and speed stays the same.