Given, accuracy of acceleration due to gravity = 4%
Accuracy of time period = 3%
Energy stored in pendulum at any instant is given as
E= ...(i)
Time period of pendulum is given by expression
T=2π√ Rearrange the above expression for L, we get
L=g()2 ...(ii)
Substituting the value of L in Eq. (i), we get
E=(T2π)2= Now, the accuracy in measurement of energy can be calculated as
×100=2×100+2×100 (∵ m,θ and π are constant)
⇒
×100=2×4%+2×3%=14% Thus, the accuracy to which E is known is 14%.