Two projectiles A and B are fired simu ltaneou ly as shown in Fig. 5.114. they colide in air at point at time t. then :

Options

A. `t(u_(1)cos theta_(1)-u_(2)costheta_(2))=20`
B. `t(u_(1)sin theta_(1)-u_(2)sintheta_(@))=10`
C. both a and b are correct
D. both a and b are wrong

Answer

b

Explanation

`x_(A)=x_(B)`
`therefore 10+(u_(1)cos theta_(1))t=30-(u_(2)cos theta_(2))t`
or `t=(u_(1)cos theta_(1)+u_(2)cos theta_(2))=20`
`y_(A)=y_(B)`
`therefore 10+(u_(1) sin theta_(1))t-(1)/(2)g t^(2)=20+(u_(2) sin theta_(2))t-(1)/(2)g t^(2)`
`therefore (u_(1) sin thete_(1)-u_(2)sin theta_(2))t=10`