Question

28. A rock falls freely from rest near the surface of a planet where the acceleration due to gravity is 4.0 meters per second. What is the speed of this rock after it falls 32 meters? (1) 8.0 m/s (2) 16 m/s (3) 25 m/s (4) 32 m/s

Answer 1

Summary of Answer:-Free fall on any other planet is similar to earth and all three equations of motion are valid.The value of acceleration due to gravity will be different for different planet.

Since lock falls freely from rest so its initial velocity will be zero i e v_i = 0 height of fall, h = 32 m gravity at that planet- g' = 4 m/s using third equation of motion we get v^2_f = v^2_i + 2g'h v^2_f = (0)^2 + 2 times 4 times 32 v^2_f = 256 v_f = squareroot 256 rightdoublearrow v_f = 16 m/s so option 2 is correct