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Grade 12th passMechanics

A ball is thrown vertically upwards with certain velocity. While moving upwards it reaches a point A at t1 second and then reaches the ground at t1+ t2
second. Find the height of point A above point of projection?

farheenkhan

9 Years agoGrade 12th pass

1 Answer

Pushkar Prateek

9 Years ago

Let initial projected speed pf ball be ‘u’ vertically up.

So in time t₁

h = ut_{1 – ½ g}t₁^{2 ( we have to find h )......................................................................(1)}

We ball returns to the ground the displacement is ZERO.

S = ut +1/2 gt²

0 = u(t₁+ t2) – ½ g (t₁+ t2)²

Solvinng quadratic,

t₁+ t2 = 0 or 2u/g (neglectinng zero as it is the initial time)

t₁+ t2 = 2u/g...............................................(2)

Substitute ‘u’ from 2 in 1

h =1/2 gt₁t2

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