A person rides a bike with a constant velocity vecvwith respect to ground and another biker accelerates with acceleration ā with respect to ground. Who can apply Newton's second law with respect to a stationary observer on the ground?

A person rides a bike with a constant velocity vecvwith respect to gro

1.	A person rides a bike with a constant velocity vecvwith respect to ground and another biker accelerates with acceleration ā with respect to ground. Who can apply Newton's second law with respect to a stationary observer on the ground?
Answer» SOLUTION :Second biker cannot apply Newton.s second law, because he is moving with ACCELERATION `veca` with respect to EARTH (he is not in inertial frame). But the first biker can apply Newton.s second law because he is moving at CONSTANT VELOCITY with respect to Earth (he is in inertial frame).