A ball is projected horizontally from the top of a cliff on the surface of the earth with a speed of 40 ms-1. Assuming that there is no air resistance, what will be its speed after 3s?
Correct answer: C. 70 ms-1
- A. 30 ms-1
- B. 40 ms-1
- C. 70 ms-1
- D. 60 ms-1
Explanation
Option C is correct.The horizontal velocity of the ball will be the same 3 seconds later. This is because there is no force acting on the ball in the horizontal direction. The vertical velocity of the ball will increase by 30 m/s after 3 seconds. This is because the acceleration due to gravity is 10 m/s² and the ball has been falling for 3 seconds. The speed of the ball 3 seconds later will be: Horizontal Velocity = 40m/sVertical Velocity = 30m/s Speed = Horizontal Velocity + Vertical Velocity = 40 m/s + 30 m/s = 70 m/s Therefore, the speed of the ball will be 70 m/s 3 seconds later.
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