Q.

A car moving with a speed of 54 km/hr takes a turn of radius 20 m. A simple pendulum is suspended from the ceiling of the car. Determine the angle made by the string of the pendulum with the vertical during the turning. (Take g=10 m/s2)                 [2026]

1 tan-1(0.5)  
2 tan-1(0.75)  
3 tan-1(1.125)  
4 tan-1(0.25)  

Ans.

(3)

Tension should be opposite to the resultant of mv2r and mg so that

the net force is zero with respect to the observer

tanθ=mv2rmg=v2rg

v=54 km/hr=15 m/s

tanθ=v2rg

⇒θ=tan-1(1.125)