Question

A car is moving along a circular track of radius $10\sqrt{3}$ m with a constant speed of 36 kmph. A plumb bob is suspended from the roof of the car by a light rigid rod of length 1m. The angle made by the rod with the track is $(g=10m{s}^2)$

• A. Zero
• B. ${30}^o$
• C. ${45}^o$
• D. ${60}^o$

Answer 1

The correct option is D ${60}^o$

36 kmph = 10m/s

$Tsin\theta =m{v}^2/r$

$Tcos\theta =mg$

dividing two equations,

$tan\theta =v^2/rg$

$tan\theta ={10}^2/\left(10\sqrt{3}\right)\ast 10=1/\sqrt{3}$

$\theta ={30}^0$

This is angle with vertical. So, angle with track is ${60}^0.$