Answer to Question #142704 in Mechanics | Relativity for Mafany

Question

A particle of mass m moves with momentum of magnitude p. (a) Show that the kinetic energy of the particle is K = p^2/ 2m. (b) An object has a kinetic energy of 275 J and momentum of magnitude 25.0 kgm/s. Find the
and mass of the object A

Answer 1

Answer

a) kinetic energy is 

$KE=\frac{mv^2}{2}$

Momentum is given by

$P= mv\\v=\frac{P}{m}$

Putting in kinetic energy become as

$KE=\frac{mP^2}{2m^2}=\frac{P^2}{2m}$ Hence proved

b) mass is given by

$m=\frac{P^2}{2K}=\frac{(25)^2}{2\times275}=1.136Kg$