Question

For ordinary terrestial experiments, which of the following observers below are inertial?

• A. a child revolving in a "giant wheel"
• B. a driver in a sports car moving with a constant high speed of 200 km/h on a straight road
• C. the pilot of an aeroplane which is taking off
• D. a cyclist negotiating a sharp turn

Answer 1

The correct option is B a driver in a sports car moving with a constant high speed of 200 km/h on a straight road

A non-inertial reference frame is a frame of reference that is undergoing acceleration with respect to an inertial frame. Thus, a body without any acceleration will always be in the inertial frame. Among the given options the child in the giant wheel has a centripetal acceleration. The pilot is taking off, thus it has a forward acceleration. The cyclist is taking a sharp turn, thus it has a centripetal acceleration. The driver is the only one moving at constant speed.
So, (B) is the correct option.