Question

If the restoring force on a body is given by: F = -kx -bv, then what is the expression for amplitude of motion? Let A be amplitude without damping forces

(a) Ae^-at, where a is some constant

(b) Ae^at, where a is some constant

(c) A

(d) 0

This question was posed to me in an online interview.

Question is from Oscillations topic in section Oscillations of Physics – Class 11

Answer 1

Right option is (a) Ae^-at, where a is some constant

To explain: The given force represents damping SHM.                                                                                                 x(t) = Ae^-atcos(bt+c).                                                                                                                                                              The term Ae^-at is the amplitude which decreases with increase in time,                                                                        until eventually the particle comes to a stop.