An object is in motion when
a.
you observe the object move.
b.
the object’s speed increases.
c.
the object’s displacement is greater than the distance traveled.
d.
the object changes position relative to a stationary reference point.

The correct answer is D. The object changes position relative to a stationary reference point.

Explanation:

Motion occurs when a specific body/object displaces or changes its position which implies the object moves from a reference point to a new one. This is usually explained as forces act over the object and make the object move or change from a stationary state to motion.

In physics, motion is widely studied according to scientific laws and this is related to main other concepts such as speed, velocity, direction, acceleration or inertia that as motion are commonly studied based on a reference system or point. According to this, it can be concluded an object is in motion if "the object changes position relative to a stationary reference point".

measure their densities same density, same sub

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.