Question

A pendulum bob is suspended from the roof of a car moving on a horizontal road with an acceleration a. The
angle made by string with the horizontal is​

Answer 1

theta = tan inverse (a/g)

a is pseudo acceleration

Answer 2

Answer:

$\phi =90^{\circ} -tan^{-1}\dfrac{a}{g}$

Explanation:

Lets take

m= Mass of bob

T= Tension in the string

Angle made from vertical = θ

a =Acceleration of the car

From diagram

T sin θ = m a

T cos θ = m g

From above equation we can say that

tan θ = a/g

$\theta = tan^{-1}\dfrac{a}{g}$

So the angle from horizontal ,Φ=90° - θ

$\phi =90^{\circ} -tan^{-1}\dfrac{a}{g}$