Makes sense, because otherwise adding pulleys would have no benefit. So then the equation is 5P+ma-mg=0, where mg=40 and m=40/32.3? Sorry, but for some reason, this problem is difficult for me to grasp.
So, to clarify, my tensions from left to right are... P/4 (for all 4) and P for the last 2... correct? And the acceleration, using v=v0+at, is 5/4 ft/s^2 upward. Then, all the tensions forces are up, mg is down, and F=ma is up, and solve for P? Seems I'm missing something.
difficulties
I am having difficulties setting it up and getting the ball rolling. There are no examples of pulley problems in this chapter. Thus far, I have figured the length of the ropes to be from left to right:
L1=y1+3*y2
L2=y2+y3
where,
y1=length to P
y2=pulley to pulley/box...
Here is the problem;
The 40-lb block is moving downward with a speed of 3 ft/s at t=0 when constant forces P and 2P are applied through the ropes. Knowing that the block is moving upward with a speed of 2 ft/s when t=4 s, determine (a) the magnitude of P. (b) the time at which the speed is 0...