Question

If a ston s to at a point which is at a distance d away and at a height h avove the point from where the stone starts, then what is the value of initial speed u if the stone is lauched at angle `theta`?

A. `g/(cos theta) sqrt(d/(2(dtan theta-h))`
B. `d/(cos theta) sqrt(d/(2(dtan theta-h))`
C. `sqrt((gd^(2))/((h cos^(2) theta)))`
D. `sqrt((gd^(2))/((d-h)))`

Answer 1

Correct Answer - b
`h=(u sin theta)t-1/2"gt"^(2)`
`d=(u cos theta)t`
`t=d/(u cos theta)`
`h=u sin theta.d/(u cos theta)-1/2g.(d^(2))/(u^(2)cos^(2)theta)`
`u=d/(cos theta)sqrt(g/(2(dtan theta-h)))`