Solution to problems – class 9 physics – Set 1 Q61, Q62, Q63

Last updated on February 12th, 2022 at 03:23 pm

Problem Statement

61) Two simple pendulums A and B have equal length, but their bobs weigh 50 gf and l00 gf respectively. What would be the ratio of their time periods ? Give reason for your answer.

Solution:
Ratio of their time periods would be 1:1.
Time period of simple pendulum is not dependent on the mass of its bob.

62) Two simple pendulums A and B have length 1·0m and 4·0 m respectively at a certain place. Which pendulum will make more oscillations in 1 minute? Explain your answer.

Solution:
Time period of A = T_a
and Time period of B = T_b
T_a / T_b =√(1/4) = ½
So T_b = 2 T_a

A will take half of the time taken by B to complete an oscillation.

So obviously pendulum A will make more oscillations in 1 minute.

63)A simple pendulum completes 40 oscillations in one minute. Find its (a) frequency, (b) time period.

Solution:
In 60 seconds it makes 40 oscillations

In 1 sec it makes = 40/60 = 2/3 oscillation

So frequency = 2/3 per second = 0.67 Hz

Time period = 1/frequency = 3/2 = 1.5 seconds

Go back to the 101 problems set (class 9)

Problems Set – grade 9