As a car drives past a person standing on a sidewalk, the driver keeps a hand on the horn. how does the pitch of the horn differ for the driver and the person standing on the sidewalk?

While the car is going towards the standing person on the sidewalk he is listening the pitch of the horn higher then it is.

When the car passes the person on the sidewalk and goes away, the horn's pitch become lower (for the person standing on the sidewalk).

For the driver, the pitch is always the same.

Explanation:

Is the doppler effect.

When the car is approaching, the sound waves must travel a smaller space than the previous one and they take less time to reach the standing person. So, sound waves reach the standing person with a higher frequency.

It happens the opposite when the car is going away: the sound waves need to travel more space and take more time to reach the person on the sidewalk. So, the frequency of the waves is lower.

moving ball hits still ball. mover stops, hit ball moves. momentum transfer.

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.