# A mass of 1x10^-16 kg is traveling, what is its kinetic energy ?

## Homework Statement

A mass of 1x10^-16 kg is traveling at 0.5 c to the nearest hundredth joule what is its kinetic energy?

## Homework Equations

Et=KE + mc^2=Jmc^2
KE=mc^2(J-1)
KE=mc^2(1/sqrt(1-v^2/c^2)-1)=

## The Attempt at a Solution

This is where i am stuck putting the whole thing in the calculator i guess...
(1X10^-16)(.5)^2(1x10^-16)(3x10^8)^2(1/sqrt(1-0.5^2)^2-1)
answer is 1.39, i keep getting something else?

sylas

## Homework Statement

A mass of 1x10^-16 kg is traveling at 0.5 c to the nearest hundredth joule what is its kinetic energy?

## Homework Equations

Et=KE + mc^2=Jmc^2
KE=mc^2(J-1)
KE=mc^2(1/sqrt(1-v^2/c^2)-1)=

So far so good.

## The Attempt at a Solution

This is where i am stuck putting the whole thing in the calculator i guess...
(1X10^-16)(.5)^2(1x10^-16)(3x10^8)^2(1/sqrt(1-0.5^2)^2-1)

This doesn't look much like the formula you just gave. The formula you had was mc^2(1/sqrt(1-v^2/c^2)-1)

How should i set the equation up ?

sylas
How should i set the equation up ?

Just use the formula you gave, with the values for all the variables. I don't know what happened for the numbers... but for example, the mass is 10-16. Mass appears just one in your formula, but twice in the list of numbers you gave for the calculator.

[highlight](1X10^-16)[/highlight](.5)^2[highlight](1x10^-16)[/highlight](3x10^8)^2(1/sqrt(1-0.5^2)^2-1)​

Can you show what to input into the calculator to get 1.39J, because that's actually where i am stuck. Thanks

Redbelly98
Staff Emeritus
Homework Helper
Can you show what to input into the calculator to get 1.39J, because that's actually where i am stuck. Thanks
No, that is not how it works at this forum.
KE = m c^2 (1/sqrt(1-v^2/c^2)-1)
.
.
.
(1X10^-16) (.5)^2 (1x10^-16) (3x10^8)^2 (1/sqrt(1-0.5^2)^2-1)
I've used color to match up the numbers in your calculation with the terms in the equation you are using. Notice that the numbers in blue don't correspond to any of the terms from the equation, and so do not even belong in the calculation.