A 4.0 kg mass of metal is dropped a distance 0.8m onto the horizontal surface in order to test its hardness.
(a) when the mass has fallen through 0.8m, how much gravitational potential energy has been transformed? [g = 10m/s2]
(b) How much kinetic energy does the mass possess before it hits the horizontal surface?
(c) What is the velocity of the body just before hitting the horizontal surface?
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Answer:
(a) Gravitational Potential Energy transformed
= mgh
= (4)(10)(0.8)
= 32 J
(b)
By the principle of conservation of energy,
Loss in PE = Gain in KE
Hence, KE = 32 J
(c) ½mv² = 32
v = √(32 * 2 / 4 )
v = 4 m/s
