Assertion (A): Electromagnetic waves do carry energy and momentum, contrary to the statement.
Reason (R): The mass of a photon is indeed zero, but this does not mean photons do not carry momentum. Photons have momentum due to their energy E = hν, which is related to their frequency ν.
As shown below, bob A of a pendulum having a massless string of length \( R \) is released from 60° to the vertical. It hits another bob B of half the mass that is at rest on a frictionless table in the center. Assuming elastic collision, the magnitude of the velocity of bob A after the collision will be (take \( g \) as acceleration due to gravity):