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A ball is gently dropped from a height of 20 \text{ m}. I... - Science
A ball is gently dropped from a height of 20 \text{ m}. If its velocity increases uniformly at the rate of 10 \text{ m s}^{-2}, with what velocity will it strike the ground? After what time will it strike the ground?
Given:
Initial velocity (u) = 0 \text{ m/s} (dropped from rest)
Distance (s) = 20 \text{ m}
Acceleration (a) = 10 \text{ m/s}^2
(i) Velocity with which it strikes the ground (v):
Using formula: v^2 - u^2 = 2asv^2 - 0 = 2 \times 10 \times 20v^2 = 400v = \sqrt{400}v = 20 \text{ m/s}
(ii) Time taken to strike the ground (t):
Using formula: v = u + at20 = 0 + 10 \times t10t = 20t = \frac{20}{10} = 2 \text{ s}
Result: The ball strikes the ground with a velocity of 20 \text{ m/s} after 2 \text{ s}.