Q: A car is moving in a circular horizontal track of radius 10 m with a constant speed of 10 m/s. A plumb bob is suspended from the roof of the car by a light rod. The angle made by the rod with the vertical is (Take g=10 m/s^{2})

(a)Zero

(b)30°

(c)45°

(d)60°

**Click to See Answer : **

Ans: (c)

Sol: Draw FBD of bob

$\large T cos\theta = mg$

$\large T sin\theta = \frac{m v^2}{r}$

on dividing,

$\large tan\theta = \frac{v^2}{r g} = \frac{(10)^2}{10\times 10}$

tanθ = 1

θ = 45°