Calculating Force of Falling Weight in Closed System

[jesuslovesu]

I'm just wondering if I'm doing this correctly..

If I have something like this: http://img326.imageshack.us/my.php?image=pull6cx.png

It's a closed system where the weights on the cart will get placed on the bottom holder for each trial... To find the 'force of the falling weight' I would take the mass*acceleration, where acceleration is determined by how fast the cart goes in a certain distance right? I wouldn't just take the mass*gravity when it's connected to a pulley like that would I?

 

[Erwin Schrodinger]

The only forces acting on the falling weight are Fg1 (force of gravity) and FT (force of tension in the rope). For the falling weight alone, Fnet1 = ma = Fg1+FT.

Since FT is applied in both directions in the rope, it "cancels out" when you involve the entire system. For the entire system, Fnet = (m1+m2)a = Fg1+Ff2.

Hope that helps.

 

[quicknote]

As a scientist, you are on the right track with your approach to calculating the force of the falling weight in a closed system.

To determine the force of the falling weight, you would indeed use the formula force = mass * acceleration. However, the acceleration in this case would not be the acceleration of the cart itself, but rather the acceleration of the falling weight. This can be calculated using the equation a = (Fnet)/m, where Fnet is the net force acting on the weight (in this case, gravity) and m is the mass of the weight.

Additionally, when using a pulley system like the one shown in your image, the force acting on the weight is not just the force of gravity, but also the tension in the rope or string connecting the weight to the pulley. This tension can be calculated using the equation T = m * g, where T is the tension, m is the mass of the weight, and g is the acceleration due to gravity.

Therefore, to calculate the force of the falling weight in this closed system, you would add the force of gravity (m * g) and the tension in the rope (T) to get the net force acting on the weight. This net force can then be used in the formula force = mass * acceleration to find the force of the falling weight.

In short, your approach is correct but make sure to consider the tension in the rope when calculating the net force acting on the falling weight.