A cartis moving horizontally along a straight line with constant speed 30m/s.At projectile is to be fired from the moving cart in such a way that it will return to the cart after the cart has moved 8Om. At what speed (relative to the cart) must the projectile be fired? (Take g=10 m//s^(2))

A cartis moving horizontally along a straight line with constant speed

1.	A cartis moving horizontally along a straight line with constant speed 30m/s.At projectile is to be fired from the moving cart in such a way that it will return to the cart after the cart has moved 8Om. At what speed (relative to the cart) must the projectile be fired? (Take g=10 m//s^(2))
Answer» `10 sqrt(8m)//s` `8sqrt(10 m)//s` `(40)/(3) m//s` None of these Solution :Time takenby the cart to cover 80M `t=(s)/(v)=(80)/(30)=(8)/(3)"Sec"` We have, `v=u=at"` `u=?,v=0, a=-g=10 m//s^(2) and t=(8//3)/(2)=(4)/(3)` (SINCE time of fight to REACH the highest point is halfofthe total time of fight) `:.0 u-10xx(4)/(3)` `u=(40)/(3)m//s`