a boy dropped a ball from the top of 20m building and starts the stopwatch . what will be the reading of stopwatch when ball will reach at ground surface, if the acceleration due to gravity is 10m/s^2?
plz answer it correctly.
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a boy dropped a ball from the top of 20m building and starts the stopwatch . what will be the reading of stopwatch when ball will reach at ground surface, if the acceleration due to gravity is 10m/s^2?
plz answer it correctly.
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s = 20m (Height)
a = 10 m/s² (Accele. due to gravity)
u = 0 (Initial velocity) [ Because Ball starts from rest]
Using 2nd Equation of motion :-
⇒ s = ut + 1/2 × at²
⇒ 20 = 0 × t + 1/2 × 10 × t²
⇒ 20 = 5 × t²
⇒ 20/5 = t²
⇒ t² = 4
⇒ t = √4
⇒ t = 2 seconds
Therefore,
Time taken by ball to reach earth's surface = 2 seconds