Mechanics M1 HELP!

[Saturation]

http://www.xtremepapers.me/CIE/Internat ... 3_qp_4.pdf

Question 5, part (ii)

I get that for block B, the equation will be: 2-0.2-T= 0.2a
But how do you do it for block A?

I don't get what the Mark Scheme says:
http://www.xtremepapers.me/CIE/Internat ... B6%2B7.pdf

HELP! Thanks!

 

[Zishi]

For block A, it's T+2-0.2=0.2a Solve the two equations for block A and B, you'll get a and T.

Alternatively you may consider it as a whole system:

4-0.4-0.2=0.4(a)

That will give you the acceleration, and put it in individual equation of A OR B to get T.

I hope it helps... :friends:

 

[Saturation]

I get the simlutaneous equation part, but what I don't get is HOW to form the the equation for A? Why is it T+2 ?
Thanks btw!

 

[Saturation]

I get the simlutaneous equation part, but what I don't get is HOW to form the the equation for A? Why is it T+2 ?
Thanks btw!

 

[Zishi]

Because the tension in the rope acting on block A is in the same direction as its weight. Remember that whenever two things are attached by a coupling, rope, OR tow-bar, the forces in the rope are always like this(irrespective of either being horizontal OR vertical)

 

[Saturation]

Oh ok! The diagram helped! Thanks!