For a wave:
v = fλ
v is the velocity, f is the frequency, and λ is the wavelength.
Assuming the velocity of the wave doesn't change...
If you increase its frequency, its wavelength will shorten.
Answer:
I think they use it at night because they want to avoid involving themselves in road accident while crossing the street. When there are reflective strips on their clothes, drivers do notice them even at far ends of the street since the strips will reflect the rays from the car lights to the driver,hence, the driver notifies that there is a pedestrian crossing and therefore slows down.
Answer:
increase the time the force acts or you could increase the number of temptations.
hope this helped!
