How Do You Calculate the Gravitational Force in a Hydrogen Atom?

[xArashix]

Homework Statement

In a hydrogen atom a electron and a proton are 1.0 x 10^-10m apart. What is the force of attraction between the two particles?

Homework Equations

F=G m1 m2/r^2

The Attempt at a Solution

electron: 9.11 * 10^31kg
Proton: 1.67 * 10^-27kg

so, Fgrav= (9.11 * 10^31kg) * (1.67 * 10^-27kg) / (1.0* 10^-10m)^2

Is this right?? And well if it is or if it isn't...how do u solve this?? I'm looking at this big equation and i don't know where to start. How do u multiply this and divide it?? I see many example problems like these and i see them going this far but them i lose them when they get the solution...how DO you get the solution??

 

[yinx]

so, Fgrav= (9.11 * 10^31kg) * (1.67 * 10^-27kg) / (1.0* 10^-10m)^2

you missed out the gravitational constant G = (6.67*10^-11)

Fgrav = (G*m1*m2)/(r^2)

multiply the numerator together first and divide it by the denominator.

 

[xArashix]

so it's... F= (6.67*10^-11)*(9.11 * 10^31kg) * (1.67 * 10^-27kg) / (1.0* 10^-10m)^2??

 

[yinx]

oh wow, so it's... F= (G*m1*m2)/(r^2)*(9.11 * 10^31kg) * (1.67 * 10^-27kg) / (1.0* 10^-10m)^2

Nope, its..

the formula is : F= (G*m1*m2)/(r^2)

so for this particular question, you need to substitute in the respective numbers..

G=(6.67*10^-11)
m1= (9.11 * 10^31kg)
m2= (1.67 * 10^-27kg)
r= (1.0* 10^-10m)

so you will get this:

F= (6.67*10^-11)(9.11 * 10^31kg)(1.67 * 10^-27kg) / (1.0* 10^-10m)^2

solve this with a calculator=)

 

[yinx]

so it's... F= (6.67*10^-11)*(9.11 * 10^31kg) * (1.67 * 10^-27kg) / (1.0* 10^-10m)^2??

yes that's correct

 

[xArashix]

solving it with the calculator is the problem T-T...how in the world do i type that in? I feel really stupid lol...how do u multiply the 10^11 and the others..I'm lost. And i bet once i figure this out I am going to feel soooo dumb :( you can't type that whole equation in the calculator so..i don't know ;_;

 

[yinx]

u need to be using a scientific calculator or a graphic calculator in order to type "10^11" are you using a scientific calculator?

and you don't have to type in the whole string of numbers in one go.

you might like to find (6.67*10^-11)*(9.11 * 10^31kg) * (1.67 * 10^-27kg) first.. followed by (1.0* 10^-10m)^2 then divide the first answer by the second answer.

 

[xArashix]

yes i do which is making me feel a lot dumber lol

if i type (6.67*10^-11)*(9.11 * 10^31kg) * (1.67 * 10^-27kg)...i get 1.01475379E-5 ...that's not right is it?

 

[yinx]

pardon me for not spotting this mistake earlier on, you mentioned you are using electrons, so the mass on electron is 9.11*10^-31 kg NOT 9.11*10^31, you missed out a negative sign. try recalculating =)

if an electron is 9.11*10^31kg in mass, its heavier than the sun! lol!

 

[xArashix]

...WOW XD I am dumb lol thanks ^^