A) \[\text{4}\sqrt{5}J\]
B) \[20J\]
C) \[10J\]
D) \[30J\]
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, \[{{v}_{B}}=\sqrt{5rg}\] \[KE=\frac{1}{2}mv_{B}^{2}\] Difference in \[KE=\frac{1}{2}m(v_{B}^{2}-v_{A}^{2})\] \[=\frac{1}{2}m(5rg-rg)\] \[=2mrg=2\times 1\times 1\times 10=20J\]You need to login to perform this action.
You will be redirected in
3 sec