Answer:
The longest wavelength of light is 209 nm.
Explanation:
Given that,
Spring constant = 74 N/m
Mass of electron 
Speed of light 
We need to calculate the frequency
Using formula of frequency

Where, k= spring constant
m = mass of the particle
Put the value into the formula


We need to calculate the longest wavelength that the electron can absorb

Where, c = speed of light
f = frequency
Put the value into the formula



Hence, The longest wavelength of light is 209 nm.
ANSWER:
250 J
STEP-BY-STEP EXPLANATION:
F = 20N is required to stretch the spring by 4 meters
We know that the force is equal to:

We solve for k (spring constant):

The work done in stretching the spring is given by the following equation (in this case the stretch is 10 meters:

The work required is 250 joules.
The ideal concept for solving this question is based on the Doppler effect, for which it is indicated that the source's listening frequency changes as the distance and the relative speed between the receiver and the transmitter are also changed. However, if the relative velocity between the two objects is zero as in the particular case presented (since both travel at 75km / h) we have that there will be no change in frequency.
Therefore the frequency that I hear and that my sister would listen would be the same.
Answer:
true
Explanation:
common sense i am just guessing.