An observer is moving in space toward a distant star at 200 km/s while the star is moving toward the observer at 400 km/s; the relative velocity being 600 km/s of approach. what relative change in frequency of the light from the star as seen by the observer? (the speed of light in space is 3.00 ´ 105 km/s).

The correct answer is: 0.2% (decrease)

Explanation:

The observed frequency can be found by using the following equation:
 --- (1)

Where  = Speed of the observer = 200 *1000 m/s
V = speed of the star = 400 *1000 m/s

Plug in the values in (1):
(1) => 

--- (2)

Change in frequency is given as: % --- (3)

Put (2) in (3):
%

=> -0.2%

Negative sign shows that it decreases!

Hence it is 0.2% (decrease).

B. convex since the words are bigger

The radiation of the fire causes the saucepan to heat up. the conduction of the saucepan then to distribute the heat over the saucepan and to give heat to the water. the convection of the water distributing the heat within the water, till all the water is boiling