Atwood's Machine

Atwood's Machine

Aim and task:

2(m1+m2)h = (MA+B)t^2

Assuming that (m1 + m2) is constant, plot a graph from which the value

of the constants A and B can be deduced. And find out what the values

should be.

Method:

Set up a pulley with 2 masses, m1 and m2 suspended on either side by a

strong thread/string so that m2 is about 1.5m off the ground when m1

is resting on it.

With m2 = 280g and m1 = 250g, obtain an accurate time for m2 to travel

from rest through the distance 'h' to the ground.

To do this, hold on mass m2 and ready to time, let m2 fall freely, and

start the timer the same time. Stop the timer when it hits the ground

(book). It will produce a loud noise when it hit the book.

Repeat this five times to get an accurate result.

Repeat the same experiment but with different values of M=(m2-m1),

where M=30,35,40,45,50,55g.

Keep (ma+m2) with 1%of 510g(i.e. constant)

[IMAGE]Diagram:

h

Working formulas out:

2(m1+m2)h=(MA+B)t^2

kh = (MA+B)t^2

kh=Mat^2+Bt^2

kh-Bt^2=Mat^2

(kh-Bt^2)/M=At^2

(((kh-Bt^2)/M)^1/2)/t=A

(2k^2)/(t^2)=MA-B

((m1-m2)*g-Ff)t=(m1=m2)2h

Ff= frictional force

Conclusion:

I have found out that A would be the gravity, and B would be the

frictional force in this equation. And the value I have found is that

A= 10, B=72 I was allowed 10% errors as I have explained in the

evaluation below, and my only have very small errors since that I knew

gravity should be about 9.8. My experiment was very well done.

Evaluations:

Over all I think my experiment went well, there were some errors, but

they were good enough to prove my theory. The errors can all be

explained. First there are some obvious errors, such as the errors

coming from the weights. Our teachers told us that the weight has

about 1% difference, so that will effects my results by 1% since that