Two cars honking at the same frequency of 800 Hz are moving toward a pedestrian standing at the curb. One car is moving with speed 25 m/s, and the second car is moving at 21 m/s. What is the frequency of the beats heard by the pedestrian? Take the speed of sound as 343 m/s.

The frequency of the beats heard by the pedestrian is 9.33 Hz

Explanation:

Frequency of the two cars, F = 800 Hz

speed of sound in air, V = 343 m/s

The sound wave length, λ = ?

λ = V / F

λ = 343 / 800

λ = 0.42875 m

The frequency of the car moving at 25 m/s heard by the pedestrian

f₁ = v₁ / λ

f₁ = 25 / 0.42875

f₁ = 58.31 Hz

The frequency of the car moving at 21 m/s heard by the pedestrian

f₂ = v₂ / λ

f₂ = 21 / 0.42875

f₂ = 48.98 Hz

The beat frequency  = f₁ - f₂

                                  = 58.31 - 48.98

                                  = 9.33 Hz

Therefore, the frequency of the beats heard by the pedestrian is 9.33 Hz

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2

it is b. absorbs thermal energy