Question

For ordinary terrestrial experiments, the observer is an inertial frame in which of the following cases?

1. A child revolving in a giant wheel
2. A driver in a sports car moving with a constant high speed of 220 kmph on a straight road
3. The pilot of an aeroplane which is taking off
4. A cyclist negotiating a sharp curve

Answer 1

(2,)

Explanation:

If an observer A is moving uniformly with respect to an inertial observer B, then A is inertial.

For terrestrial observations, an observer fixed to the earth can be considered (approximately) inertial. (This observer does accelerate with respect to the distant stars, but compared to the typical terrestrial accelerations she observes, her own acceleration is tiny).

Of the four options, only the second is moving uniformly with respect to the earth.