A plank of mass m is lying on a rough suface having coeffient of frinction as `mu` is situation as shown in fig Find the acceleration of the plank assuming that it slips and the surface of body exposed to radiaton is black body.

Explanation

`E=` Energy received by surface per second is
`IAcostheta=Iabcostheta`
Number of photons reveived by the surface per second ,
`N=(E)/((hc)/(lamda))=(Iabcosthetalamda)/(hc)`
`triangleP_(`one photon)`=(h)/(lamda)`
`impliesf_(radian)=triangleP_(o n e pho t on)` `N=(Iabcostheta)/(c)`
Let us draw the FBD of the plank (see fig.)
`Fsintheta-muN=malpha`...(i)
`N=mg+Fcostheta`...(ii)
From Eqs. (i) and (ii), we get
`alpha=(Fsintheta-mu(mg+Fcostheta))/(m)`