8) These two pulleys are attached together on a common axle. The larger one has a radius twice as large as the smaller o
Posted: Mon Jul 11, 2022 1:14 pm
- 8 These Two Pulleys Are Attached Together On A Common Axle The Larger One Has A Radius Twice As Large As The Smaller O 1 (553.28 KiB) Viewed 29 times
N mg scripts.mit.edu i) The image to the left shows the forces acting on a disk rolling down a ramp. The first time we found the acceleration of such a disk, we had to put the reference point for torques at its center. The result? We threw away the weight of the disk and were left with two unknowns, the friction force and the acceleration. Why did we have to do that? a. Torques must be taken around the center of the object. b. 1-2/3 MR¹ c. I = MR² d. 1 = 3/2 MR¹ b. We eliminate two forces that way. We only knew 1 (iota) for an axis through the center. d. That's the natural center of rotation, so we must use it. 12) We found the acceleration of the disk again, this time using the Parallel Axis Theorem, so that we could place the reference point for torques at the spot where the disk touches the ramp. Which expression gives the correct value for the rotational inertia of the disk in that case? a. I = ½ MR¹ 13) If the disk has a mass of 0.75 kg, a radius of 0.15 m, and is 0.050 m thick, and if the ramp is inclined 20° from the horizontal, then what is the disk's linear acceleration down the ramp? a. 2.23 m/s² b. 6.14 m/s² c. 6.53 m/s² d. We can't say, as the acceleration increases as it rolls. 14) That image is from a website at the prestigious Massachusetts Institute of Technology (MIT). Despite that, what is wrong with it? a. The normal force, N, is mg cos 0 and so should be smaller than mg, not larger. b. The friction force, f, is uN and so should be smaller than both N and mg. c. Both a and b are true. d. Oh, nothing could POSSIBLY be wrong with it, because it IS from MIT!