Recent content by harvey1999

it's shown in my textbook without explanation, so I'm quite confused.

I have been trying to search for answers on the Internet, but to no avail. For induced magnetism, i understand that a magnetic material can turn into an induced magnet under the influence of a magnetic field. However, i do not understand how to magnetic poles are determined. Suppose a perm...

however, it is true that if R=A+B, then delta(R) = delta(A) + delta(B). i don't get what you mean by independent though. I'm sorry but i just want to fully understand this, thank you!

i'm sorry, what do you mean by counting 1/40 twice? is my method not the correct approach anyway?

V=(pi)(R^2)(L) - (pi)(r^2)(L) delta(R)=(1/2)(0.2)=0.1cm delta(r)=(1/2)(0.2)=0.1cm delta(V) = delta(pi*R^2*L) + delta(pi*r^2*L) Let x=(pi)(R^2)(L) delta(x)/x = 2(0.1/6) + 1/40= 7/120 delta(x)=7/120 * (pi*R^2*L)=7/120 * 14 400 pi = 840pi Let y=pi*r^2*L delta(y)/y = 2(0.1/5) + 1/40=13/200...

A manufacturer needs to determine the volume of metal used to produce a metal pipe of the following dimensions: Length, L 40 + 1 m External diameter, D 12.0 + 0.2 cm Internal diameter, d 10.0 + 0.2 cm Estimate the greatest possible percentage error of the volume. the correct ans is...

thank you

but what about the normal force, which is the reaction force of air on shelf, after the shelf acts on the air? Or is it if i exert 10N on the shelf, the shelf absorbs some and only exerts part of 10N on the air?

why?

To protect a place from magnetic fields, soft iron is placed around the place, right? so when magnetic field passes through the soft iron, the soft iron becomes an induced magnet, thereby creating induced fields, which makes no sense as the induced fields would still hit the place. please...

i don't get what you mean if i can push a shelf through air, force of shelf on air is actually not 10N?

So here it goes. If I am pushing an object, say is shelf. I apply a force of 10N on it, it accelerates, and it exerts 10N back on me. I understand this, but correct me if i am wrong. Now, the shelf also exerts a force of 10N on the air particles while it is moving. Shouldn't the air particles...