Question

A car is moving in a circular horizonta track of radius 10m with a constant speed of 10 m/s. A pendulum bob is suspended from the roof of the cat by a light rigid rod of length 1.00m. The angle made by the rod with track is
A. zero
B. `30^@`
C. `45^@`
D. `60^@`

Answer 1

Correct Answer - C
When the car is moving in a horizontal track of radius `10 m` with constant speed, then the bob is also under going a circular motion. The bob is under the influence of two forces.

i. `T` tension in the rod)
ii. mg( weight of the bob)
Resolving tension, we get
`Tcostheta=mg`.....i
and `T sin theta=(mv^(2))/r`............ii
(Here `Tsintheta` is producing the necessary cenripetal force for the circlar motion)
dividing eqn i and ii we get
`tantheta=(v^(2))/(rg)=(10x10)/(10xx10)=1impliestheta=45^@`