Astronomers use the color of stars to determine how hot they are and their brightness to estimate how far away they are. <em>(D)</em>
Potential energy does.
A book on the floor has negative potential energy relative to the seat
of your chair, zero potential energy relative to the floor, and a whole
bunch of positive potential energy relative to the ground if the floor
is the floor of the passenger jet in which you are cruising and dropped
your book on the floor.
Answer:
1. Reflection
2. travel from one medium to another
3. Same waves to travel in opposite direction.
Explanation:
1. When a wave strikes a solid barrier, it bounces back in the same medium. This wave behavior of bouncing back is known as reflection. Its like a basketball hitting a backboard. The ball bounces back at the same angle as it was incident. ∠i = ∠r
2. For refraction to occur in a wave, the wave must travel from one medium to another. When light travels from through mediums of different optical densities, it bends. The wave bends away normal when it enters from denser medium to rarer medium. The wave bends towards the normal when it enters from rarer to denser medium. The angle of refraction and angle of incidence are related by Snell's law.

3. The formation of standing wave requires two same waves to travel in the opposite direction and interfere. The incident wave and reflected wave when interfere, form standing waves. There waves are also resonances or harmonics. A standing wave oscillates at one place and does not transfers any energy.
<h2>Potential energy lost by 10 N rock will be greater</h2>
Explanation:
Two rocks of 5N and 10N falls from the same height . Thus they will loose the potential energy.
The potential energy lost = mass x acceleration due to gravity x height
The potential energy lost by first 5 N rock = 5 h
Because weight of rock m g = 5 N
Similarly , the potential energy lost by 10 N Rock = 10 h
here weight of rock m g = 10 N
Thus comparing these two , the potential energy lost by 10 N rock is greater than that of 5 N rock .
Answer:
v = 8.4 m/s
Explanation:
The question ays, "A longitudinal wave has a frequency of 200 Hz and a wavelength of 4.2m. What is the speed of the wave?".
Frequency of a wave, f = 200 Hz
Wavelength = 4.2 cm = 0.042 m
We need to find the speed of the wave. The formula for the speed of a wave is given by :

So, the speed of the wave is equal to 8.4 m/s.