Expert: Sherman D. - 8/15/2005

Question
1.)  An object has a mass of 120 kg on the moon.  What is the force of gravity acting on the object on the moon?  B.)20N C.)196N D.)1,176N

2.)  If a stone with an original velocity of 0 is falling from a ledge and takes 8 sec. to hit the ground, what is the final velocity of the stone?  A.)39.2 m/s B.)42.6 m/s C.)78.4 m/s

3.)  An object with a mass of 78 kilograms is lifted through a height of 6 meters.  How much work is done?  A.)47.75J C.)764.4J D.)4,586.4J

4.)  If an object has a mass of 20 kg, what is thr force of gravity acting on it on earth?  A.)196N B.)2.04kg D.)1.96kg  

Answer
1.)
the moon's gravity is (1/6) of the earth's gravity

F = ma
F = Mass * Acceleration

Am = (9.8)/6 = 1.63333333

F = 120kg * 1.63333333

F = 196N

ANS : C.) 196N

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2.)
Vf = Vo + at
Vf = 0 + (9.8 * 8)
Vf = 78.4

ANS : 78.4m/s

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3.)
Work = Fd
W = (78 * 9.8) * 6
W = 764.4 * 6
W = 4586.5J

ANS : D.) 4,568.4J

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4.)
F = ma
F = 20kg * 9.8
F = 196N

Is the same thing as 1. because (120/6) = 20

ANS : A.) 196N