A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building.
What is the minimum amount of work that the worker did in lifting the bucket? A) 3.92 kJ
B) 400 J
C) 560 J
D) 4.08 kJ
E) 160 J
Question 2
A heavy frog and a light frog jump straight up. They push off in such a way that they both have the same kinetic energy just as they leave the ground. Assume air resistance is negligible.
Which of the following statements about these frogs are correct? (There could be more than one correct choice.) A) Just as they leave the ground, the heavier frog is moving faster than the lighter frog.
B) Just as they leave the ground, the lighter frog is moving faster than the heavier frog.
C) They both leave the ground with the same speed.
D) The lighter frog goes higher than the heavier frog.
E) The heavier frog goes higher than the lighter frog.
F) Both frogs reach the same maximum height.
Teresa Hubbard and Alexander Birchler, Detached Building.
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