A box slides down a rough ramp.
The change in the gravitational potential energy of the box is 16 J as it moves between positions X and Y. The box has 24 J of kinetic energy at X and 35 J of kinetic energy at Y.
How much work is done against the frictional force?
A 5 J
B 19 J
C 27 J
D 43 J
ANSWER: A
The Physics Behind
- Energy is conserved. The total energy at X must be equal to the total energy at Y.
- At X,
- 16 J of potential energy
- 24 J of kinetic energy
- At Y,
- 0 J of potential energy [at reference point]
- 35 J of kinetic energy
- energy lost
- The energy lost is due to work done against friction.
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