What is the Force F acting on a NdYAG laser of 1 kW ?

[ammar98]

Homework Statement

Force F acting on a NdYAG laser of 1 kW continuous wave output by the impulse transfer of the photons

Homework Equations

F= dp/dt

The Attempt at a Solution

Photon Energy E=[hc][/λ]=hν
momentum P= [h][/λ]
power of laser 1 kw
at time (t) the laser emit photons
t=[P][/E] = [λ[/hc]

F= dp/dt = t * P = [λ][/hc] * [h][/λ] = [1][/C] = 3.333 x 10 ^ -9 N

can you check please if the solution correct

 

[kuruman]

Homework Statement

Force F acting on a NdYAG laser of 1 kW continuous wave output by the impulse transfer of the photons

Homework Equations

F= dp/dt

The Attempt at a Solution

Photon Energy E=[hc][/λ]=hν
momentum P= [h][/λ]
power of laser 1 kw
at time (t) the laser emit photons
t=[P][/E] = [λ[/hc]

F= dp/dt = t * P = [λ][/hc] * [h][/λ] = [1][/C] = 3.333 x 10 ^ -9 N

can you check please if the solution correct

You need to provide the photon wavelength without which we cannot check your solution.

F= dp/dt = t * P= [λ][/hc] * [h][/λ] = [1][/C] = 3.333 x 10 ^ -9 N

If P is power (Energy per unit time) then t*P is energy not force. Also 1/c has units of Time/Length which is not units of force.

 

[scottdave]

Where do you include the 1 kW power? It doesn't appear that you have.

Please provide numbers which you use (like wavelength of a NdYAG laser) to make it easier to check your calculations.

Another tip: try to make sure your capital P is consistent meaning Power, and momentum symbol is ρ (which you can get by clicking the Σ icon above the text box) or just use lower case p.