Answer to Question #71423 in Mechanics | Relativity for Bindu

Question

A car is moving on a plane inclined at 30° to the horizantal with an accelearation of 9.8m/s^2 parallel tobthe plane upwards.A bob is suspended by a string from the roof. The angle in degrees which the string makes with vertical is: (assume that bob doesn't move relative to car)

Answer 1

the string should be parallel to the total vector of acceleration which is the sum of the gravitational acceleration g=9.8 m/s^2 and the movement of the car acceleration (a=9.8 m/s^2). These vectors have the same magnitude, so the total one will be between them, hence the angle is the half of the given one 30°/2=15°