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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 its speed be 3 s later?

Correct answer: C. 50ms−1

  • A. 30 ms−1
  • B. 40 ms−1
  • C. 50ms−1
  • D. 60ms−1

Explanation

50ms−1: Correct. Understanding Projectile Motion and Velocity: The horizontal velocity remains constant (40 m/s). The vertical velocity increases due to gravity (v = gt). We need to find the resultant velocity.Calculations:Vertical velocity (vy) = g * t = 9.8 m/s² * 3 s = 29.4 m/s (approximately 30 m/s)Resultant velocity (v) = √(vx² + vy²) = √(40² + 30²) = √(1600 + 900) = √2500 = 50 m/s

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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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