Question

4.80-kg watermelon is dropped (zero initial speed) from the roof of a 25.0-m-tall building. a) Calculate the work done by gravity on the watermelon during its displacement from the roof to the ground. b) What is the kinetic energy of the watermelon just before it strikes the ground? You can ignore air resistance.
Work is force times distance

Force is mass times acceleration

Your acceleration is g=9.8 m/s, mass is 4.8 kg

So force is 9.8*4.8= 47 kg m/s, and distance is 25m

(a) Work then becomes 25*47=1176 J

Kinetic energy is the same as work, since you don't have any air resistance. KE=1176J

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