In Newton's second law lab, there are two cases.

In the first case, the track is level. The second case has the track inclined. I am going to draw a free-body diagram (two actually) for the inclined case. I think this will help you out some with the lab and with your lecture course perhaps. Here is a diagram of the situation.



Here is the free body diagram with the forces on both objects.



A couple of important things to note:
- The magnitude of the tension on the cart is the same as the magnitude of the tension on the hanging mass
- The normal force on the cart is normal to the track. Since the track is not horizontal, the normal force is not vertical (I see this mistake all the time)
- I have chosen to have the x-axis parallel to the track. This is a good thing because the acceleration of the cart is in the x-direction AND the acceleration of the cart in the y-direction is zero.
- This x- and y-axis does not apply to mass 2, which can have a normal axis.
- The tension in the string is NOT the weight of mass 2 (unless it is balanced, but that is a special case).

Ok, now for the hint. Let me look at Newton's second law for the red cart. I can write Newton's second law as two equations:



What forces are acting in the x-direction? The answer is: the tension and part of the weight of mass-1. I can write the x-forces equation as:



Note that θ is the angle the track is inclined. If you can't see where that componet comes from, draw a picture to help with your geometry. The y-forces equation will be:



Now for the hanging mass. The y-force equation for it is:



There is one more trick. Since the two objects are connected by a string, they must have the same magnitude of acceleration. So, the a's would be the same. Now you have a case where you have two equations two unknowns and you should be able to finish from there.

Hope that hint helps.