In which situation is mechanical energy conserved?
A. a parachutist descends at constant speed
B. a car slows down without braking along a flat road
C. a heavy crate is raised at constant speed via a rope andpulley system
D. a sled accelerates as it slides down a frictionless inclinedplane
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Two spaceships have the same mass. Spaceship A has kineticenergy K and spaceship B has kinetic energy 16K. What is the ratioof their speeds, vA/vB?
A. 1/16
B. 1/8
C. 2/1
D.  1/4
