Question

A ball is dropped from the roof of a building . It takes 10 seconds to reach the ground . Find the height of the building . (Take g = 9.8 m/s^2)

Answer 1

Given:
Initial speed =u = 0 m/s( free fall)

Time =t = 10 sec

a=g= 9.8m/ s2

Height = h = ?

Formula to be used:

Second equation of motion:

h= ut + 1/2at^2

h= 0xt+(1/2)×9.8 × 10x10
= 4.9 x 100
= 490m

Therefore the height of building is 490m.

Answer 2

The object is dropped , so the initial velocity ,(u) = 0

Acceleration is the acceleration due to gravity ‘g’ = 9.8m/s² (given)

Time travelled( t) =10 sec (given)

‘h’ is distance travelled (Height of the tower )


h =ut+(1/2)gt²

h=0× 10 + (1/2)× 9.8 × 10²

h= 0 + 4.9 × 100

h= 490m


Hence, the height of the tower is 490 m.

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Hope this will help you...