A man is sitting on the shore of a river. He is in the line of a 1.0 m long boat and is 5.5 m away from the centre of the boat. He sishes to throw an apple into the boat. If he can throuw the apple only wihta speed of 10 m/s, find the minimum and maximum angles of projection for successful shot. Assume that the point of projection and the edge of the boat are in the same horizontal level

Answer

A, B, C, D

Explanation

When the apple just touches the end B of the boat.
`x=5m, u=10 m/s, theta= ?, g= 10 m/s^2`
` x= (u^2 sin 2theta)/g`
`rarr 5=((10)^2 sin 2theta)/10= 10 sin 2theta`

`rarr sin 2theta = 1/2 = sin 30^0 or sin 150^0`
`rarr theta = 15^0 or 75^0`,
Similarly for end C, x=6 m ltbr. Then `2 theta = sin^-1 ((gx)/u^2)`
`=sin^-1 (0.6) = 18^0 or 71^0`
so, for a successful shot theta may vary from `15^0 to 18^0 or 71^0 to 75^0`.