A) \[4\sqrt{5}\,\,J\]
B) 20 J
C) 10 J
D) 30 J
Correct Answer: B
Solution :
Kinetic energy is the energy possessed by a body of mass m due to its velocity v. \[KE=\frac{1}{2}m{{v}^{2}}\] At the highest point velocity, \[{{v}_{A}}=\sqrt{rg}\] \[\therefore \] \[KE=\frac{1}{2}mv_{A}^{2}\] At the lowest point velocity, \[{{v}_{B}}=\sqrt{5\,rg}\] \[KE=\frac{1}{2}mv_{A}^{2}\] Difference in\[KE=\frac{1}{2}mv_{B}^{2}-v_{A}^{2}=\frac{1}{2}m\,(5rg-rg)\] \[=2mrg=2\times 1\times 1\times 10=20\,J\]You need to login to perform this action.
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