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Points P, Q and R are in vertical line ...

Points ` P, Q` and `R` are in vertical line such that ` PQ =QR`. A ball at (P) is allowed to fall freely. What is the ratio of the times of descent through PQ and QR ?

A

0.042361111111111

B

1 : `sqrt 2`

C

`1 : (sqrt 2` - 1)

D

1 : (`sqrt 2` + 1)

Text Solution

Verified by Experts

The correct Answer is:
(c )
PQ=QR=h
`h=1/2"gt"_(1)^(2)` and `2h=1/2g(t_(1)+t_(2))^(2) (therefore u=0)`
`1/2=(t_(1)^(2))/(t_(1)+t_(2))^(2)` or `1/sqrt(2)=(t_(1))/(t_(1)+t_(2))`
`t_(1)+t_(2)=sqrt(2)t_(1)` or `t_(1)(sqrt(2)-1)=t_(2)`
`therefore t_(1)/t_(2) = 1/(sqrt(2)-1)`
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