Answer:
when a two bodies A and B are moving at an angle 180° with each other then the relative velocity is the sum of bodies the velocity .i.e,
when the bodies move the opposite direction
then their relative velocity is the sum of individual velocities.
You'd use the equation kinetic energy=mass*0.5*speed^2
So you'd rearrange this to get mass =kinetic energy /0.5 *speed^2
Which is mass= 1500J/0.5*35^2
=2.44897959183673469........kg
Answer:

Explanation:
Due to the law of conservation of energy, the energy of the emitted X-ray photon is equal to the energy lost by the electron.
The initial kinetic energy of the electron is:

The electrons decelerates to 3/4 of its speed, so the new speed is

So the final kinetic energy is

So, the energy lost by the electron, which is equal to the energy of the emitted photon, is

The wavelength of the photon is related to its energy by

where h is the Planck constant and c the speed of light. Substituting E, we find
