Machines B/C

[Godspeed]

Thanks, Umaroth for pointing out that you can't calculate the AMA of the system, thus making parts c and d impossible.

Wow!! So it wasnt just me thank God. I was kinda scared to ask ngl.

Nope, It wasn't! When in doubt, I probably wrote the question wrong...

Yeah I thought I was just dumb and didn't know the AMA. If not specified tho, isn't the AMA always the same as the IMA if you're not given any extra information such as friction?

[RiverWalker88]

Wow!! So it wasnt just me thank God. I was kinda scared to ask ngl.

Nope, It wasn't! When in doubt, I probably wrote the question wrong...

Yeah I thought I was just dumb and didn't know the AMA. If not specified tho, isn't the AMA always the same as the IMA if you're not given any extra information such as friction?

Generally speaking, yes, you will assume IMA and AMA are the same for a system, especially if the question states that the system is ideal. However, if you specifically are asked for AMA, you will probably have to find some way to get the effort and resistance forces to do this. I gave no effort force for this, so it was impossible to solve for the AMA.

[Godspeed]

Nope, It wasn't! When in doubt, I probably wrote the question wrong...

Yeah I thought I was just dumb and didn't know the AMA. If not specified tho, isn't the AMA always the same as the IMA if you're not given any extra information such as friction?

Generally speaking, yes, you will assume IMA and AMA are the same for a system, especially if the question states that the system is ideal. However, if you specifically are asked for AMA, you will probably have to find some way to get the effort and resistance forces to do this. I gave no effort force for this, so it was impossible to solve for the AMA.

Oh I see, ok.

[YellowMamba]

Is e 5827.14 joules?

[RiverWalker88]

So, for the scattered answers (thanks for posting, this was a very poorly-written question, sorry ) here's the solutions.

1. Block & Tackle
2. IMA = 4. There are two moving pulleys, so the IMA is 2*2=4
3. This is why I should solve
4. problems before posting them.
5. I got 1903 J, because I used the frictional force that needs to be overcome for the force that the block was pulled at. Once again, though, this part was unclear and far too open to assumption...

So, yeah. Someone's turn now. Next time I post a question, I will solve it first to ensure clarity and possibility. Apologies for the bad question.

[astronomybuff]

Alright, it's been a while.

A block slides down a plane inclined at an angle of θ degrees with constant velocity. It is then projected up the same plane.

Determine the following (symbolically)
a) Coefficient of kinetic friction
b) The distance it travels before it stops
c) Whether or not it will slide down again

[astronomybuff]

Hello....
Don't leave me hanging guys

[Hiujier]

a)

Click to Show Answer

Since the block slides down parallel to the plane at a constant velocity, we know that the net force parallel to the plane is 0. Drawing a free body diagram and writing Newton's 2nd Law, we get:

b)

Click to Show Answer

I'm not sure if you can find the distance without initial velocity at the bottom of the ramp, so here is my solution given intial velocity:

Using energy conservation with work done by friction, we get:

,

where  is the distance traveled by the block parallel to the plane.

Furthermore, we know from part (a) that:
, so:

c)

Click to Show Answer

When the block is at rest after sliding, we know it experiences static friction. For static friction, we know that:



From this, we know that:
,


So the combining both conditions we get that the net force must be 0 when the block is at rest at the top of the plane. Therefore, it will not slide down again.

[astronomybuff]

Yep! Everything correct. Yes, my bad I forgot to include the velocity with which it was projected is v0. Your turn!

[Ttonyxx]

Okay, I'll guess I'll go since no one else is going.

1) Let's start easy: What are the three Archimedean simple machines?
2) A little harder: What is the ideal mechanical advantage of a 0.112in-40 UNC-3A x 0.5 screw? Explain what each of the numbers in the screw callout means.
3) In the diagram shown below, the block has a mass m = 100kg and there is a coefficient of friction μ = 0.203 between the surfaces on the top and bottom of the wedge. The angle of the wedge (between the two contact surfaces) is 15°. Assume every other surface is frictionless and the only moveable pieces are the wedge and the block. Calculate the force P required to raise the block.