Density: g/mL, kg/cubic meter
Volume: L, teaspoon
Mass: g, MeV/sq. C
For this case we have that by definition, a micrometer is equivalent to a thousandth of a millimeter, that is, 0.001 millimeters.
Then, in other words, we have 0.001 millimeters in a micrometer.
Answer:
In a micrometer there are 0.001 millimeters.
When the roller coaster going down
step by step
Answer:
853776 J
Explanation:
The work-energy needs to pump water out of the pool is the product of the weight of water and distance h
E = Wh = mgh
Since water mass is a body of water we can treat it as the product of density 1000kg/m3 and volume, which is the product of base area and uniform height h
Therefore:
![E = mgh = g\rho A\int\limits^{2.2}_0 {h} \, dh\\E = 9.8*1000*30*12[h^2/2]^{2.2}_0 = 1764000(2.2^2 - 0^2) = 853776 J](https://tex.z-dn.net/?f=E%20%3D%20mgh%20%3D%20g%5Crho%20A%5Cint%5Climits%5E%7B2.2%7D_0%20%7Bh%7D%20%5C%2C%20dh%5C%5CE%20%3D%209.8%2A1000%2A30%2A12%5Bh%5E2%2F2%5D%5E%7B2.2%7D_0%20%3D%201764000%282.2%5E2%20-%200%5E2%29%20%3D%20853776%20J)
Explanation:
They probably put "rolls without slipping" in there to indicate that there is no loss in friction; or that the friction is constant throughout the movement of the disk. So it's more of a contingency part of the explanation of the problem.
(Remember how earlier on in Physics lessons, we see "ignore friction" written into problems; it just removes the "What about [ ]?" question for anyone who might ask.)
In this case, you can't ignore friction because the disk wouldn't roll without it.
As far as friction producing a torque... I would say that friction is a result of the torque in this case. And because the point of contact is, presumably, the ground, the friction is tangential to the disk. Meaning the friction is linear and has no angular component.
(You could probably argue that by Newton's 3rd Law there should be some opposing torque, but I think that's outside of the scope of this problem.)
Hopefully this helps clear up the misunderstanding for you.
