Recent content by skysunsand

Yeah, that was my failure to mention the pulley is massless and frictionless. I was never quite sure why they made a point to mention that. Thank you for clarifying that. Fn is my notation for normal force. I checked my calculations per what you said about converting and I ended up with...

How does that change my equations?

Homework Statement A 200N block is on a 35 degree incline with a frictionless, massless pulley and a weight on the other side, Fw= 220. The system is in equilibrium. What are the magnitude and direction of the frictional force on the 200N block? Homework Equations and The Attempt at...

Homework Statement A horizontal force F is exerted on a 20kg box to slide it up a 30 degree incline. The friction force retarding the motion is 80N. How large must F be if the acceleration of the moving box is to be .75 m/s^2? Homework Equations All the forces on the box in the x and y...

Yeah, you'd set T=4a + 4g , plug that into the other equation for T, to get 12g+(-4a-4g) = 12a to get 8g=16a 8*9.8 = 16a a=4.9 Ah. I must have screwed up somewhere in my algebra. Thank you!

Homework Statement A cord passing over a frictionless, massless pulley has a 4.0 kg object tied to one end and a 12 kg object tied to the other. Compute the tension and acceleration in the cord. Right now, I'm just trying to calculate the acceleration. It is supposed to be 4.9 m/s^2...

Homework Statement A kayaker needs to paddle north across a 100-m-wide harbor. The tide is going out, creating a tidal current that flows to the east at 2.0 m/s. The kayaker can paddle with a speed of 3.0 m/s. Homework Equations v= v + V Let the Earth frame be S and a frame attached...

Well, it would mean everything has to equate out to 0. With the forces, I think there's the force of tension + mg on the 200 weight, multiplied by two because there's two strings supporting the weight. And then there's gravitational force on the 500 N plank. So then for the forces, it...

So that's where he gets L1- each of them are turning by themselves, so they're just (1/2 MR^2 + 1/2 MR^2)w1. But then okay, the second one is where you have to put them into parallel axis. I= I + MR^2 is the equation for parallel axis. All I understand is that maybe you still put 1/2...

I'm absolutely, hopelessly bad at physics. I have no clue how any of this is coming together, conceptually. Here's all I understand: I1w1 + I1w1 = I2W2 So supposedly, for some reason, you can plug in the parallel axis theorem, I guess to all of the I's to get- (I+MR^2)w1 +...

Then wouldn't it just be MR^2, because then it's a point mass?

I = 1/2 Mr^2. So then putting that into either equation would give1/2 Mr^2 = 1/2 Mr^2 + Mr^2 and 1/2Mr^2 w1 + 1/2 Mr^2w1 = 1/2 Mr^2w2

They've stuck together and are spinning like that. I don't get how he's using the parallel axis theorem to get any of that. I can se how maybe I1w1 + I1w1 = I2W2, because momentum is conserved, but where does parallel axis fit in there? Attached is the picture.

Homework Statement See attachment! A plank is 4m long and has a weight of 500 N. It is pivoted frictionlessly about a nail which is driven through the center of the plank. When a 200 N weight is hung as shown in the figure (attached), the plank is horizontal and in equilibrium. Suppose...

Homework Statement I'm working through a practice test my professor has given us. The question is as follows: Two uniform solid cylinders, each with radius R and mass M are spinning about their individual axes, with angular velocity w1, each in a counterclockwise direction. They are...