4. A guitar emits a 440 Hz tone. How far apart are the crests in room temperature air (20 °C)? How long does it take the string to vibrate from crest position to trough position (across
twice the amplitude)?

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

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.