Waves get their energy from the wind.
Answer:
The time of short pulse of light beam is 
Explanation:
Given that,
A beam of light from a laser illuminates a glass.
Suppose, the length of piece is 
Index of refraction is 2.83.
We need to calculate the speed of light pulse in glass
Using formula of speed

Put the value into the formula


We need to calculate the time of short pulse of light beam
Using formula of velocity


Put the value into the formula


Hence, The time of short pulse of light beam is 
A.
The planet contains matter and energy so it is a system.
Answer: find the answer in the explanation
Explanation:
Average velocity is the average value of magnitude of initial velocity and final velocity.
If U = initial velocity and V = final velocity, then average velocity can be expressed as
Average velocity = ( U + V )/2
A vehicle who takes 60 minutes to cover 30 miles north and then 30 miles south and end up at the same place, has an average speed of 60 miles divided by 60 minutes, or 1 mile per minute.
Instantaneous velocity is the distance covered in a specific direction per time taken. Instantaneous velocity can be expressed as
Velocity = displacement/ time.
Uniform velocity occurs when we have a constant velocity. That is, when velocity does not change. When a vehicle travels in equal distances in equal intervals of time.