Question : A cart is moving horizontally along a straight line with constant speed30 ms−1 . A projectile is to be fired from the moving cart in such a way that it will return to the cart has moved 80 m. At what speed (relative to the cart) must the projectile be fired? (Take 𝑔 = 10 ms−2 )
(A) 10ms^{-1}
(B) 10\sqrt{8}ms^{-1}
(C) \dfrac{40}{3}ms^{-1}
(D) None of the above
Answer : option (C)
Solution :

