In frame S (Earth's frame), a ball is dropped from rest from a height h above the ground. Another frame S' is moving upward with a uniform speed u with respect to the Earth. In frame S', the initial downward speed of the same ball is v. Considering the difference in measuring the change in kinetic energy (ΔK) until just before the ball hits the ground in frames S and S', which one of the following is correct?

In frame S (Earth's frame), the ball starts from rest and reaches a velocity v_f = √(2gh) just before hitting the ground. ΔK in S = (1/2)m(2gh) - 0 = mgh. In frame S' moving upward with speed u, the initial velocity of ball is v (downward, where v = u since initially the ball is at rest in S and S' moves up at u). When the ball hits the ground, its velocity in S' is √(2gh) + u (both downward). The change in KE in S' = (1/2)m(√(2gh) + u)² - (1/2)mu² = (1/2)m[2gh + 2u√(2gh)] = mgh + mu√(2gh). Since this is greater than mgh, ΔK is greater in frame S'. Therefore, option (c) is correct.