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
(c ) when the car is moving in a circular horizontal track of
radius 10 m with a constant speed, then the bob is also
undergoing a circular motion. The bob is under the influence
of two forces.
(i) T (tension in the rod)
(ii) mg(weith of the bob)
Resolving tension, we get
`T cos theta = mg ....(i)`
And `T sin theta = (mv^2)/(r ) ....(ii)`

(Here `T sin theta` is producing the necessary centripetal
force for circular motion)
Dividing (ii) by (i) we get
`tan theta = (v^2)/(rg) = (10xx10)/(10xx10) =1 rArr thet = 45^@.`