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Physics homework help?
A massless spring with force constant k = 208 N/m hangs from the ceiling. A 2.1 kg block is attached to the free end of the spring and released. If the block falls 16 cm before starting back upwards, how much work is done (in J) by friction during its descent?
2 Answers
- ?Lv 75 months agoFavorite Answer
GPE becomes SPE and friction work
2.1kg * 9.8m/s² * 0.16m = ½ * 208N/m * (0.16m)² + W
W = 0.63 J
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- FiremanLv 75 months ago
The initial PE of the mass = mgh = 2.1 x 9.8 x 0.16 = 3.29 J
The final PE of the spring = 1/2kx^2 = 1/2 x 208 x (0.16)^2 = 2.66 J
By work energy relation,
=>W(friction) = ΔPE = The initial PE of the mass - The final PE of the spring
=>W(f) = 3.29 - 2.66 = 0.63 J
