What is the momentum of a proton moving at 0.7c?

[ZedCar]

Homework Statement

A proton of rest mass 1.67 x 10^-27 kg is moving at a constant speed of 0.7c

What is it's momentum?

Homework Equations

The Attempt at a Solution

Using E = γmc^2 I obtained;

E = 2.10 x 10^-10 JThen with;

E^2 = (pc)^2 + (mc^2)^2 and solving for p I got;

p = 8.47 x 10^-15

 

[Redbelly98]

Homework Statement

A proton of rest mass 1.67 x 10^-27 kg is moving at a constant speed of 0.7c

What is it's momentum?

Homework Equations

The Attempt at a Solution

Using E = γmc^2 I obtained;

E = 2.10 x 10^-10 J

I agree.

Then with;

E^2 = (pc)^2 + (mc^2)^2 and solving for p I got;

p = 8.47 x 10^-15

That's the correct method, but I'm getting something quite different. It is probably just an arithmetic mistake. Can you show more details of this calculation?

 

[ZedCar]

I agree.That's the correct method, but I'm getting something quite different.

Are you getting 4.88 x 10^-19 ?

 

[Redbelly98]

Yes, with units of kg*m/s.