One of the two mathematical pendulums made 10 oscillations, and the other during the same time – 6 oscillations.
One of the two mathematical pendulums made 10 oscillations, and the other during the same time – 6 oscillations. the difference in the lengths of the pendulums is 16 cm. Determine the lengths of the pendulums.
N1 = 10.
N2 = 6.
t1 = t2 = t.
ΔL = 16 cm.
L1 -?
L2 -?
The period of the mathematical pendulum T is determined by the formula: T1 = t1 / N1 = t / N1,
T2 = t2 / N2 = t / N2.
t = T1 * N1.
t = T2 * N2.
T1 * N1 = T2 * N2.
The period of a mathematical pendulum is determined by another formula: T1 = 2 * п * √L1 / √g, T2 = 2 * п * √L2 / √g.
2 * п * N1 * √L1 / √g = 2 * п * N2 * √L2 / √g.
N1 * √L1 = N2 * √L2.
N1 ^ 2 * L1 = N2 ^ 2 * L2.
L1 = N2 ^ 2 * L2 / N1 ^ 2.
ΔL = L2 – L1 = L2 – N2 ^ 2 * L2 / N1 ^ 2 = L2 * (1 – N2 ^ 2 / N1 ^ 2).
L2 = ΔL / (1 – N2 ^ 2 / N1 ^ 2).
L2 = ΔL / (1 – N2 ^ 2 / N1 ^ 2).
L2 = 16 / (1 – 36/100) = 25 cm.
L1 = L2 – ΔL.
L1 = 25 cm – 16 cm = 9 cm.
Answer: L2 = 25 cm, L1 = 9 cm.