Question

A ball thrown in vertically upward direction attains maximum height of 20 meter. At what height would its velocity be half of its initial velocity ?
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Answer 1

Answer:

Step by step solution by

Solution

For motion of a ball in vertically upward direction, suppose v0= initial velocity = ?.

v = velocity at maximum height (20m)=0.

a=−gandd=20m

From equation 2d=v2−v20, we get,

−2g×20=(0)2−v20

∴−40g=−v20

∴v20=40g ...(1)

Now, suppose velocity at height h=v=v02

∴ From equation 2ad=v2−v220, we get,

−2gh=v204=(∵a=−g,d=h,v=v02)

∴−2gh=−3v204

∴−h=3v204×2g

∴h=3×40g8g (From eq. (i))

∴h=15m