Connected Pully question

[coooool222]

I'm having trouble doing this, Here my work so far:
Equations to use : s = r * theta

So the unknown radius wheel is
450 = r * 5pi/4 (I converted 225 degrees to radians
114.59 = r ?????

I'm having trouble with the angle part, is the 10-inch circle, a 10 radius circle?? If so this is what I did
450 = 10 * theta
45 = theta ????

Since this is a pulley they both move at the same time at the same distance

 

[coooool222]

Im not allowed to do proportions btw

 

[topsquark]

View attachment 36509
I'm having trouble doing this, Here my work so far:
Equations to use : s = r * theta

So the unknown radius wheel is
450 = r * 5pi/4 (I converted 225 degrees to radians
114.59 = r ?????

I'm having trouble with the angle part, is the 10-inch circle, a 10 radius circle?? If so this is what I did
450 = 10 * theta
45 = theta ????

Since this is a pulley they both move at the same time at the same distance

I think it would be a good idea if you could post a diagram of this. I can think of some three ways to invalidate this whole process, depending on the setup. We need to know where the wheels are, and how they are connected.

-Dan

 

[coooool222]

I think it would be a good idea if you could post a diagram of this. I can think of some three ways to invalidate this whole process, depending on the setup. We need to know where the wheels are, and how they are connected.

-Dan

 

[Dr.Peterson]

View attachment 36509
I'm having trouble doing this, Here my work so far:
Equations to use : s = r * theta

So the unknown radius wheel is
450 = r * 5pi/4 (I converted 225 degrees to radians
114.59 = r ?????

I'm having trouble with the angle part, is the 10-inch circle, a 10 radius circle?? If so this is what I did
450 = 10 * theta
45 = theta ????

Since this is a pulley they both move at the same time at the same distance

I would expect a "10-inch wheel" to have a diameter of 10 inches. You can probably check whether such phrases have that meaning by looking around in your book.

The theta you calculate will be in radians, of course, so you'll probably want to convert to degrees.

But the fact that the information about the 10-inch wheel seems irrelevant to the question asked makes me suspicious of the setup. (You could use it, but that would mean using a proportion, which you say for some reason you were told not to use; and that's a lot of extra work.)

 

[topsquark]

View attachment 36511

Okay, so
[imath]s = r \theta = R \Theta[/imath]

I agree with Dr.Peterson, the 10 inches is likely a diameter. So
[imath]450 = 5 \theta = R \dfrac{5 \pi}{4}[/imath]

What doesn't make sense to me here is that we do not need to know anything about the (supposedly) larger wheel.

But, your approach should give you the correct answer.

-Dan

 

[Steven G]

I think it would be a good idea if you could post a diagram of this. I can think of some three ways to invalidate this whole process, depending on the setup. We need to know where the wheels are, and how they are connected.

-Dan