Thread: Physics Quiz 12
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Unread 03-03-2016, 16:53
Rachel Lim Rachel Lim is online now
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Re: Physics Quiz 12

I attempted this yesterday, and I'm still not sure if I'm doing this correctly. I feel like I'm missing some step, but what I've done so far is below.

Assumptions / notes for part 1:
- The only thing that matters is the gravity component parallel to the rail, and the tension force parallel to the rail.
- The cart moves as a single body along the rail (it doesn't matter which part of the cart the rope is attached to)
- The 0.5 m/s is irrelevant, what does matter is that it's moving at a constant velocity (i.e. acceleration = net force = 0)

Part 1:
T = 5448 N

I'll post a picture of my working when I get a chance, but basically what I had was:
F_gravity = F_tension
m*g*sin(20deg) = T cos(12deg)
(All are the component parallel to the 20deg rail)

Assumptions / notes for part 2:
- The angle of the rope is less than the angle of the rail, so the cart is being pulled "into" the rail.
- This creates torque around point G and the cart is basically being twisted.

Part 2:
I'm not entirely sure how to do the calculations on this, but I'm guessing it results in rollers A and C being pulled "down" and B and D pulled "up."

Last edited by Rachel Lim : 04-03-2016 at 13:43. Reason: Not sure where I thought there was a ramp...
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