Question

An object has a total energy that is 2.8 times its rest energy.

Part A

Part complete

What is its speed?

Express your answer using two significant figures.

v =

0.93

c

SubmitPrevious Answers

Correct

Part B

What is the ratio of the object’s relativistic kinetic energy to its rest energy?

Express your answer using two significant figures.

Answer 1

Object's rest energy

E_o=m_oc²

Given E_total=2.8E_o =2.8m_oc²

1-(V/c)² =(1/2.8)²

V/c =sqrt[0.8724]

V=0.934c

b)

Relativistic kineitc energy

K=m_oc²[1/sqrt[1-0.934²] -1]=1.8mc²

Therefore

K/E_rest =1.8m_oc²/m_oc² =1.8