7. What do you mean by kinetic friction.
8. Define Kinematics and Kinetics of particle. A train runs at a speed of 120km/hr in
curved track of radius 900m the application of brake suddenly, causes the train to slo
down at a constant rate. After 6 seconds the speed has been reduced to 72km/h
Determine the acceleration immediately after the brakes is applied.
​

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m