A ball is dropped from a height of 45m above the ground. Calculate the velocity...
PHYSICS
WAEC 1994
A ball is dropped from a height of 45m above the ground. Calculate the velocity of the ball just before it strikes the ground. (Neglect air resistance and take g as 10ms?2
- A. 21.2ms?1
- B. 30ms?1
- C. 300ms?1
- D. 450ms?1
Correct Answer: B. 30ms?1
Explanation
\(v^2 = u^2+2as=0^2 + 2\times 10\times 45 \Rightarrow
v^2 = 900m^2s^{-2} \Rightarrow \\
v = \sqrt{900m^2s^{-2}} \Rightarrow
v = 30ms^{-1}\)
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