# Homework Help

#### PhysicsIsVeryFun23

I was able to easily find A, yet for b and c i am very confused on how to solve it. For b i did 2(mass of proton) + 2(mass of neutron) = mass of alpha particle
But i don't see how to find the energy from that. Then afterwards i don't see how to find the speed.

#### topsquark

Forum Staff
An alpha particle is a Helium nucleus. How does the mass of Helium differ from your calculation? You can convert this mass difference into energy using the usual $$\displaystyle E = mc^2$$.

Here E = KE. So what is the formula for kinetic energy?

-Dan

#### PhysicsIsVeryFun23

An alpha particle is a Helium nucleus. How does the mass of Helium differ from your calculation? You can convert this mass difference into energy using the usual $$\displaystyle E = mc^2$$.

Here E = KE. So what is the formula for kinetic energy?

-Dan
Oh so I would do 1/2mv^2 =mc, also would the mass in this case be the 2(mass of proton) + 2(mass of neutron) - mass of alpha particle

#### topsquark

Forum Staff
Oh so I would do 1/2mv^2 =mc, also would the mass in this case be the 2(mass of proton) + 2(mass of neutron) - mass of alpha particle
I presume there's a typo: $$\displaystyle \dfrac{1}{2}mv^2 = mc^2$$.

Otherwise, yes!

-Dan

#### PhysicsIsVeryFun23

I presume there's a typo: $$\displaystyle \dfrac{1}{2}mv^2 = mc^2$$.

Otherwise, yes!

-Dan
Ok perfect and yeah i was quoting the equation you typed. The mobile had a typo

topsquark