two balls are thrown simultaneously,A vertically upwards with speed of 20m/s from the ground and B

Asked by  | 23rd Jul, 2009, 02:27: PM

Expert Answer:

Let the two balls meet at distance x from the ground after time t.

For ball A:

u = 20 m/s; g = 10 m/s2; h = x

using h = u t - (1/2) g t2

x = 20 t - 5 t2 -------------(1)

For ball B:

u = 0; g = 10 m/s2; h = 40 - x

using h = u t - (1/2) g t2

40 - x =  5 t2 -------------(2)

Using eq. (1) and (2)

40 - 20 t + 5 t2 = 5 t2

t = 2 s

From eq. (1), x = 20 m

 

Answered by  | 24th Jul, 2009, 10:37: AM

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