Answer:
Magnitude of the vector is
and the direction is 
Explanation:
Magnitude of first vector = 
Angle = 
Magnitude of second vector = 
Angle = 
x component of first vector

y component of first vector

x component of second vector

y component of first vector

Adding the magnitudes


Magnitude of the sum of the vectors would be

The direction would be

The magnitude of the vector is
and the direction is 
<span>speed = wavelength x frequency
speed = 0.4m X 10 Hz
speed = 4 m/s</span>
Need more than that to answer this question
<u>C</u> is the correct answer, because energy cannot be created neither destroy. The energy is changing from chemical to from electric to light, and from light to heat.