A cricket ball is thrown at a speed of ` 28 ms^(-1)` in a direction `30 ^(@)` above the horizontal. Calculate (a)the maximum height (b) the time taken by ball to return ti the same level, and (c )the distance from the thrower to the point wher the ball restance from the throwrt to the point where the ball returns to the same level.

Options

A. ` 10.0m` `2.8 s` `29 m`
B. ` 10.0m` `2.8 s` `69 m`
C. ` 10.0m` `3.8 s` `69 m`
D. ` 20.0m` `2.8 s` `69 m`

Answer

B

Explanation

a) the maximum height is given by
`h_(m) = (v_(0)sintheta_(0))^(2))/(2g) = (28sing30^(@))^(2)/(29.8)` m
`=(14 xx 14)/(2 xx 9.8) = 10.0m`
b) The time taken to return to the same level is `T_(f) = (2v_(0)sintheta_(0))^(2))/(2(9.8))`m
`=(14 xx 14)/(2xx 9.8)=10.0m`
The time taken to return to the same level is `T_(f) = (2v_(0)sintheta_(0))//g = (2 xx 28 xx sin30)/(9.8) = 69 m`