Question

A small object at rest, absorbs a light pulse of power 20 mW and duration 300 ns. Assuming speed of light as 3 × 10⁸ m/s. the momentum of the object becomes equal to

(1) 0.5 10^-17 kg m/s 

(2) 2 x 10^-17 kg m/s

(3) 3 x 10^-17 kg m/s

(4) 1 x 10^-17 kg m/s

Answer 1

(2) 2 x 10^-17 kg m/s