SOMEBODY LITERALLY HELP- no kidding I JUST WALKED UP THE STAIR OF MY HOUSE AND saw someone I thought was my sister. no one was there... THIS HAPPENED 20 MIN EARLIER AND NOT TOO LONG AGO I HEARD A KNOCK ON THE DOOR no one was at the other side-

i believe the answer is a

resonant frequency

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.