1.

A cart is moving horizontally along a straight line with constant speed `30 ms^-1.` A particle is to be fired vertically upwards from the moving cart in such a way that it returns to the cart at the same point from where it was projected after the cart has moved `80 m.` At what speed (relative to the cart) must the projectile be fired? (Take `g = 10 ms^-2`)A. `10 ms^-1`B. `10 sqrt8 ms^-1`C. `40/3 ms^-1`D. None of these

Answer» Correct Answer - B
`t=(80m)/(30m//s)=8/3s.`
Now in vertical direction `t=(2u_r)/(a_r)`
or `u_r=(ta_r)/2 (a_r=g=10m//s^2)`
`=((8//3)(10))/2`
`=40/3 m//s`


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