Answer:
31.2 m/s
Explanation:
= Frequency of approach = 480 Hz
= Frequency of going away = 400 Hz
= Speed of sound in air = 343 m/s
= Speed of truck
Frequency of approach is given as
eq-1
Frequency of moving awayy is given as
eq-2
Dividing eq-1 by eq-2


= 31.2 m/s
Trust me, i'm a k12 student and its motor
The energy of a photon is given by

where

is the Planck constant
f is the frequency of the photon
In our problem, the frequency of the light is

therefore we can use the previous equation to calculate the energy of each photon of the green light emitted by the lamp:
1. If we increase the distance to twice it's original value, the light intensity is reduced by one-fourth, the light intensity would be:
I0/4
2. rms magnetic field is inversely proportional to distance, so the new rms magnetic field would be:
B0/2
3. average energy density is inversely proportional to the square of the distance, so the new average energy density is:
E0/4
<span>b.) Add heat to increase the molecular motion of the atoms</span>