Question

A car is moving horizontally along a straight
line. A ball is projected from this car in such
a way that it will return to it after it has
moved 100 m. The speed of the ball is (in
ms")
1) 9.8 2) 19.6 3) 15.6
3) 15.6 4) 24.6
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Answer 1

Answer:

u=10g√sin2θ.

Explanation:

The ball returns to the car after it has moved 100 m.

⇒ The ball has been projected upward with velocity, u⃗ , at an angle, θ , to the horizontal.

Since the ball returns to the car after a certain distance it implies that the distance covered by the car during this time is same as the range of the projectile.

⇒ The range, u2sin2θg=100.

⇒u=10g√sin2θ.

Thus, it can be seen that the magnitude of the initial velocity is a function of the angle of projection, as given above.