How Far Will M1 Travel in 0.633 Seconds?

[jap90]

The problem is this: There are two blocks of unknown masses M1 and M2. M1 is sitting on a frictionless table and M2 is attached to m1 by a massless string and is hanging over the edge over a pulley. If m1 is four times more massive than m2, how far will m1 travel in 0.633 seconds?
So far I've gotten
a= (m2/m1+m2)g .
I replaced m1 with 4*m2, and then simplified the equation to give me
a=(1/5)g
a=(1/5) 9.8
a= 1.96 m/s^2.

Once I had the acceleration, I then used the fact that a=v/t to give me the velocity, and then I multiplied the velocity by the time to give me distance.
a=v/t
1.96=v/.633 sec
v=1.24m/s
I then multiplied that by the time in order to give me the distance.
v*t= 0.785 m

I entered this into the homework on the internet and it says I'm wrong, I don't know what else to do? Can anyone help me on where I messed up?
thanks

 

[6Stang7]

it's not a=v/t, but a=dv/dt.

you did solve for v correctly and a correctly though and you almost have the right answer. the error is in the last part of your work.

what does (velocity)(time)=distance mean?

 

[kyle8921]

It looks like you did all the calculations correctly. However, it's possible that there was a rounding error or a mistake in the problem itself. I would recommend double-checking your calculations and also checking with your instructor to see if there were any specific instructions or conditions for the problem that you may have missed. It's also possible that the online homework system has a different answer key or is not accepting the correct answer. In any case, it's always a good idea to double-check your work and seek clarification if needed.