A car rounds a 75-m radius curve at a constant speed of 18 m/s. a ball is suspended by a string from the ceiling the car and moves with the car. the angle between the string and the vertical is:

The angle between the string and the vertical is computed by:

Centripetal acceleration Ac = V²/R = 18²/75 = 4.32 m/s² horizontal

Gravitational acceleration g = 9.8 m/s² down

Θ = arctan (Ac/g)

= arctan (4.32m/s^2 / 9.8 m/s^2)

= 23.79° is the answer.