A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms\(^{-1}\) from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is? (Take g = 10ms\(^{-2}\))
- 5J
- 10J
-
15J
- 20J
The correct answer is: C
Explanation
Givn
m = 0.1kg
u = 10ms\(^{-1}\)
h = 10m
g = 10ms\(^{-2}\)
At h\(_{max}\); v = 0
Using
\(\not v\) = \(\not u\) = \(\not gt\)
\(\not 0\) = \(\not w\) - \(\not 10t\)
v\(^{2}\) = u\(^{2}\) - 2gh
0\(^{2}\) = 10\(^{2}\) - 2 x 10h
20h = 100
h = 5m
Total height = 10 + 5
= 15m
Total energy = mghr = 0.1 x 10 x1 5
= 15J
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