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


Answer: 4
Explanation:
Given that:
Mass of car M = 2200 kg
Initial speed Vi = 50 km/hr
Final speed Vf = 100 km/hr
Kinetic energy is the energy possessed by a moving object. It is measured in joules, and depends on the mass (m) of the object and the speed (v) by which it moves
i.e K.E = 1/2MV^2
So, when traveling at 50 km/h
KE = 1/2x 2200kg x (50km/h)^2
KE = 0.5 x 2200 x 2500
KE1 = 2750000J
So, when traveling at 100 km/h
KE = 1/2x 2200 x (100 km/h)^2
KE = 0.5 x 2200 x 10000
KE2 = 11000000J
Thus, the number of times kinetic energy increases is obtained by dividing KE2 by KE1
i.e 11000000J / 2750000J
= 4
Thus, the kinetic energy from the car’s forward motion increase 4 times