A balloon floats inside a stopped car. When the car starts moving forward, the balloon appears to move backward relative to the car. Which statement best explains this observation?

Question

a. The motion of the car creates an unbalanced backward force on the balloon.
b. The force of inertia on the balloon balances the force from the motion of the car.
c. The car moves forward, while inertia keeps the balloon in place.
d. Inertia prevents the force of the car from acting on the balloon.

Answer 1

The best explanation for the observation that the balloon appears to move backward relative to the car when the car starts moving forward is:

c. The car moves forward, while inertia keeps the balloon in place.

This is because the balloon, being in a state of rest, tends to remain at rest due to inertia. When the car accelerates forward, the balloon does not immediately follow the motion and instead appears to move backward relative to the car.