13. A man standing on a bus remains still when the bus is at rest. When the bus moves forward and then slows down the man continues moving forward at the original speed. This is an example of the effect of A. gravity. B. inertia. C. velocity. D. weight.

The right option for this question is option “B” and that is
inertia. The man and the bus are both static in the first instance. In the
second instance the bus starts moving forward and then slows down, but it can
be seen that the man is standing in the same place but his upper torso is
trying to move forward. This is because of the inertial effect. The part in
contact with the bus stops as soon as the bus stops, but the upper torso still
is in motion at which the bus is moving. This has been well defined by Newton’s
first law.