physics
posted by Josh on .
These are problems I have been stuck on and can't figure out. Help would be greatly appreciated.
1. Blue and yellow light combinte to produce white light because ______ (Please explain what it's the correct answer)
a.they absorb each other's wavelengths
b. blue, yellow and white are primary colors
c. they constructively interfere
d. they destructively interfere
e. none of the above
2. You see lightning and then count 4 seconds till you hear the thunder. From this you conclude that the lightning strike occured_______ (how do I calculate it?)
a. 1400m away
b. 700m away
e. none of the above
3. Does sound travel faster in water or air? Justify
4.You are standing on the beach and you notice 4 waves travel over your feet in 8 seconds. Your friend is 4 meters away from you in the water and you count 3 waves between you. How fast do the waves travel on water?
5. You shine yellow light on an object and it appears black. Whta color might the object be if illuminated by red light? why?
6. A Gatling gun fires at a rate of 2000 rounds per minute. If the bullets travel at a speed of 800m/s how far apart are the bullets?

1. Blue and yellow light doesn't make white light. On a white surface, you will see green reflected. On a yellow surface, you will see yellow, on a blue surface, you see blue, on a black surface, you see black. e is the answer.
2. What is the velocity of sound? It takes 5 seconds to go 1600 meters.
3. water of course. The density of water is greater.
4. frequency*lambda= speed
4/8 * 4/3= speed
You better memorize this equation.
5. yellow light on black is black. Red light on black is black.
There are other answers: Blue
6. in 60 seconds, there are 2000 rounds in the air, and they cover a distance of 800m. Distance apart= 800/2000 m