Question

a body is projected vertically upwards with a velocity u,aftet time t another body projected vertically upwards with a velocity v, where v less than u.if meet at what time​

Answer 1

Answer:

Let v be initial velocity of vertical projection and t be the time taken by the body to reach a height h from ground.

Here, u=u,a=−g,s=h,t=t

Using, s=ut+21​at2, we have

h=ut+21​(−g)t2 or gt2−2ut+2h=0

∴t=2g2u±4u2−4g×2h

​​=gu±u2−2gh

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It means t has two values, i.e.,

t1​=gu+u2−2gh

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t2​=gu−u2−2gh

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t1​+t2​=g2u​ or u=2g(t1​+t2​)​