A body is projected horizontally from the top of a cliff with a velocity of 9.8m/s. What time elapses before horizontal and vertical velocities become equal? Take g = 9.8m/s2
Correct answer: D. 1s
- A. 9.8s
- B. 0s
- C. 10s
- D. 1s
Explanation
To solve the problem, we use the following steps:1. The horizontal velocity (Vx) remains constant at 9.8m/s, as there is no acceleration in the horizontal direction.2. The vertical velocity (Vy) can be calculated using the formula Vy = gt, where g = 9.8m/s2.3. We set the horizontal velocity equal to the vertical velocity: Vx = Vy = 9.8m/s.4. Substitute the values: 9.8 = 9.8t, solving for t gives t = 1s.Therefore, the time elapsed before the horizontal and vertical velocities become equal is 1 second.The other options are incorrect because they either confuse the initial velocity with time or miscalculate the time taken for the velocities to become equal.
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Displacement, velocity and acceleration describe motion, including the horizontal and vertical components of projectile motion. The chapter connects these quantities with Newton's laws, momentum and impulse, then applies conservation of momentum to collisions, distinguishing elastic collisions from inelastic ones.
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