Question

A car moves horizontally with a constant acceleration of $3m/s^2.$ A ball is suspended by a string from the ceiling of the car. The ball does not swing, being at rest with respect to the car. What angle does the string make with the vertical?

• A. ${17}^o$
• B. ${35}^o$
• C. ${52}^o$
• D. ${73}^o$

Answer 1

The correct option is A ${17}^o$

The condition for the ball to be moved backward is the horizontal component is accelerating at the rate of $3m/s^2$

Hence by using

$F=mg\sin \theta$

$mg\sin \theta =3m$

$\theta ={\sin }^{-1}\left(\frac{3}{10}\right)$

$\theta ={17}^{\circ }$

Hence, the angle that the string makes with the vertical is ${17}^{\circ }$