The correct answer to the question is: A) miles/hour and B) metre/ second.
EXPLANATION:
Before answering this question, first we have to understand speed.
The speed of a body is defined as the rate of distance travelled or the distance travelled by a body per unit time.
Hence, it is a derived quantity which is obtained from distance and time.
The unit of distance can be metre, miles, and the unit of time can be second, minutes or hour.
As speed is the distance covered per unit time, the perfect units will be miles/hour and metre/second.
Hence, the correct options are first and second.
The answer is 24N. Since the body is moving with constant velocity all the forces must balance (equal & opposite)
when the two waves interfere with eachother to make a dark spot the periodic difference of the two waves is π . the wave length for 2π is 600nm
. ie. for π difference it is 300nm
When A Light Ray Hits A Boundary,,,,, it is called refraction.
