Answer:
The thermal energy is the sum of the potential energy and kinetic energy that is known to make all the particle in an object it is the energy that is responsible for its temperature heat is the flow of thermal energy thermal energy is the result of something that has some internal temperature which can be measured
The answer would be D, electromagnetic waves
Explanation:
Given that,
The mean kinetic energy of the emitted electron, 
(a) The relation between the kinetic energy and the De Broglie wavelength is given by :



(b) According to Bragg's law,

n = 1
For nickel, 



As the angle made is very small, so such an electron is not useful in a Davisson-Germer type scattering experiment.
Answer:
R = 73.25 m
Explanation:
We have,
Initial speed of the ball is 27 m/s
It is projected at an angle of 40 degrees
The maximum range of the ball is given by :

Plugging all the values we get :

So, the maximum range of the ball is 73.25 m