You and your dog are standing on the side of the road. Someone approaches in a very fast car playing an eigth octave C on a piccolo (4186 Hz). How fast would they have to approach in m/s so that only your dog would hear the piccolo

vs > 271.21 m/s

Explanation:

The audition interval of a dog is between in 20  to 65,000 Hz. For human is in between 20 to 20,000 Hz.

In order to obtain a velocity that only the dog is be able to hear, you can consider that the perceived frequency is higher, at least, than 20,000 Hz.

This problem is about Doppler's effect. To calculate the speed of the source of the sound (a car playing a piccolo), you use the following formula for the case on which the source is getting closer to the observer:

       (1)

f: frequency of the source = 4186Hz

f': frequency perceived by the observer = 20,000Hz

v: speed of sound = 343 m/s

vo: speed of the observer = 0m/s

vs: speed of the source = ?

You solve the equation (1) for vs and replace the values of the other parameters:

The speed of the car must be vs > 271.21 m/s

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force