a. An object with a mass of 10.0 kg is at a height of 100 meters over the ground

Question

a. An object with a mass of 10.0 kg is at a height of 100 meters over the ground. Using the ground as your reference height (0 m), determine the object's potential energy when at its original height.

Answer:__________ Joules

b. Now determine the object's potential and kinetic energies after it has fallen to a height of 50.0 m

Potential energy Answer:______ Joules

Kinetic energy Answer:_________ Joules

c. Finally, determine the object's potential and kinetic energies just prior to the moment of impact.

Object's kinetic energy upon impact

Answer:_______ Joules

Object's potential energy upon impact

Answer:________ Joules

Explanation / Answer

Given that

mass of object m = 10kg

height of object over ground H = 100 m

Accelaration due to gravity g = 10 m/s2

a) Potential energy at its original height P.E = mgH = 10x10x100 = 10000 J

b) Potential energy potential energy of oject at height h= 50 m is P.E = 10x10x50 = 5000 J

Velocity of object V = (2gh)1/2 = (2x10x50)1/2 = 31.62 m/s

Kinetic energy of the object at height 50 meters is K.E = mV2/2 = 10(31.62)2/2 = 5000 J

c) Final velocity of the object is V= (2x10x100)½ = 44.72m/s

The Kinetic energy of the object at just before imfact K.E = 10(44.72)²/2 = 10000J

and the potential energy of the object at just before imfact P.E = 0J ( just before impact, consider h =0)

(If we consider h=99.9999m just before impact then K.E.= 9999J and P.E.=1J)

If consider g = 9.8 m/s2

a) potential energy = 9800J

b) potential energy at 50m height =4900J

Kinetic energy at 50m height = 4900J

c) kinetic energy before impact = 9800J

Potential energy before impact = 0J

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