PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics
Problem
A metro train is initially at rest at a platform. It soon starts moving, travels with uniform velocity for some time and then applies brakes to stop at the next station. A passenger standing inside the coach experiences different effects during these three stages.
(i) When the train just starts, the passenger feels a backward jerk. Identify the type of inertia involved and explain the reason briefly.
(ii) While the train is moving with uniform velocity, the passenger drops a small coin from shoulder height. The coin lands exactly at the passenger’s feet. Explain how this observation is connected with the concept of inertia.
(iii) As the train comes to a sudden halt at the next station, the passenger lurches forward. Name the type of inertia exhibited here and justify your answer.
(iv) Suggest one safety device used in trains or buses that makes use of the same principle of inertia to protect passengers, and explain its working in two sentences.