ONE CAN perform this by doing an ideal experiment
by creating an isothermal system
its like you supply heat to a body and that body is present at very low temperature the amount of heat you supply is equal to the amount of heat lost by that body due to difference in the temperature of the body and the surrounding. heating curve will be constant as there is no change in the internal energy of the system ..
Velocity is speed with direction. So, if velocity varies directly with speed, that statement would be true. A constant velocity would resort in a constant speed. They are connected and are dependant on each other.
I hope this helps!
~kaikers
Answer:
Part a)

Part b)

Explanation:
Part a)
Level of sound = 75 dB
now we know that

here we know that

now we have


Part b)
Intensity of sound wave is given as

here we know that

so we have


now we know



now we have


Newton's third law: If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A. This law represents a certain symmetry in nature: forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself.