Answer:
26036485.6433 W/m²
Explanation:
E= Energy = 470 J
t = Time = 4 seconds
d = Diameter = 2.6 mm
Power is given by

Intensity is given by

The intensity of the laser beam is 26036485.6433 W/m²
Answer:
Interference of light
Diffraction of light
Polarization of light
Reflection of light
all show the wave nature of light.
Compare the initial mass to the final mass.
Answer:
v = 12.86 km/h
v = 3.6 m/s
Explanation:
Given,
The distance, d = 13.5 km
The time, t = 21/20 h
= 1.05 h
The velocity of a body is defined as the distance traveled by the time taken.
v = d / t
= 13.5 km / 1.05 h
= 12.86 km/h
The conversion of km/h to m/s
1 km/h = 0.28 m/s
12.86 km/h = 12.86 x 0.28 m/s
= 3.6 m/s
Hence, the velocity in m/s is, v = 3.6 m/s