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A ball of mass 0.1kg is thrown vertically upwards with a ...

A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms1 from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is? (Take g = 10ms2)

A.

5J

B.

10J

C.

15J

D.

20J

Correct answer is C

m = 0.1kg
u = 10ms1
h = 10m
g = 10ms2

At hmax; v = 0

Using
= = t
0 = - 10t

v2 = u2 - 2gh
02 = 102 - 2 x 10h
20h = 100
h = 5m
Total height = 10 + 5
= 15m
Total energy = mghr = 0.1 x 10 x1 5
= 15J