Question

A ball is dropped from the top of a building the ball takes 0.5 s to fall past the 3 m length of a window at certain distance from the top of the building. Speed of the ball as it crosses the top edge of the window is `(g=10 m//s^(2))`
A. `v_(T)+v_(B)=12 ms^(-1)`
B. `v_(B)-v_(T)=4.9 ms^(-1)`
C. `v_(B)v_(T)=1 ms^(-1)`
D. `v_(B)/v_(T)=1 ms^(-1)`

Answer 1

Correct Answer - A::B
`v_(B)=v_(T)+9.8xx0.5=v_(T)+4.9` ltbgt `v_(B)=v_(T)=4.9 m//s` and
`v_(B)^(2)-v_(T)^(2)=2gs=2xx9.8xx3=58.8`

`rArr (v_(B)+v_(T))xx(v_(B)-v_(T))=2xx9.8xx3`
`rArr v_(B)+v_(T)=12 m//s`