PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics
Problem
A bus is initially at rest on a straight road. A passenger is standing in the aisle without holding any support. Just after the bus suddenly begins to move forward with a uniform acceleration, the passenger appears to be thrown backward relative to the bus.
(i) Draw a free-body diagram of the passenger immediately after the bus starts moving, as seen by an observer standing on the road.
(ii) Identify all the external forces acting on the passenger and state their directions.
(iii) Explain, with the help of Newton’s first law of motion, why the passenger appears to be thrown backward even though no backward force acts on him.