The ceiling of a hall is 40m high. For maximum horizontal distance, the angle at which the ball may be thrown with a speed of `56ms^(-1)` without hitting the ceiling of the hall is

Options

A. `25^(@)`
B. `30^(@)`
C. `45^(@)`
D. `60^(@)`

Answer

b

Explanation

`h=(u^(2)sin^(2) theta)/(2g)=((56)^(2)sin^(2) theta)/(19.6)`
`sin^(2) theta=(40xx19.6)/((56)^(2))=1/4`
`sin theta=1/2 or theta=30^(@)`