chpt. 21, ex. 21.8 A laser has a power of 22.0 W and a beam radius of 0.500 mm.
ID: 2013867 • Letter: C
Question
chpt. 21, ex. 21.8A laser has a power of 22.0 W and a beam radius of 0.500 mm.
a. Find the intensity of the laser.
b. Suppose you were floating in space and pointed the laser beam away from you. What would your acceleration be? Assume your total mass, including equipment, is 72.0 kg and that the force is directed through your center of mass.
c. Compare the acceleration found in part (b) with the acceleration of gravity of a space station of mass 1.00 x 10^6 kg, if the station's center of mass is 100.0 m away.
Explanation / Answer
A laser power has P = 22.0 W radius of beam is r = 0.500mm a ) Intensity of the beam is I = P / r^2 = 22.0 W / ( 0.500*10^-3m)^2 = 2.80*10^7 W/m^2 b ) Given that mass is m = 72.0kg Force F = p / t = 2 I A / c = 2 ( 2.80*10^7 W /m^2) ( 0.500*10^-3m)^2 / 3.00*10^8 m/s = 7.326*10^-8 N acceleration a = F /m = 7.326*10^-8 N / 720 kg = 1.02*10^-9 m/s^2 c ) Acceleration due to gravity is g = G m / r^2 = 6.67*10^-11 * 1.00*10^-6 kg / (100m)^2 = 6.67*10^-9 m/s^2Related Questions
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