Recent content by david456103

anyone?

Suppose we want to find the electric field of a line of uniform charge at a height x from the line. Why can we only apply Gauss's law if the line is of infinite length or if x is small compared to the length of the line of charge?

but how do you find that tension?

Homework Statement A piece of string of length l and mass M is fastened into a circular loop and set spinning about the center of a circle with uniform angular velocity omega. Find the tension in the string. Suggestion: Draw a force diagram for a small piece of the loop subtending a small...

Hi everyone, Let me just give you some background on my physics knowledge/experience. I am a rising sophomore in high school and my freshman year I self-studied AP Physics C and am almost 100% sure I scored a 5. Right now I'm studying for the USAPhO. I have the book Introduction to Mechanics by...

For calculating I of a uniform solid sphere, why can't we use thin spherical shells? When I try to use spherical shells I get (3/5)MR^2. Every single derivation uses thin cylindrical shells and end up with the correct expression((2/5)MR^2) but they never explain why it is correct to use...

@truesearch i think you have the wrong problem in mind, but yeah your thinking process is exactly the one I feel is right. Here is the problem I'm concerned about(from MITOCW): A spherical billiards ball of uniform density has mass m and radius R and moment of inertia about center of mass of...

let's consider the problem when a ball initially at rest on a surface with friction is given a horizontal impulse. According to some online sources, the ball will eventually attain a maximum speed after it is given the impulse. However, this makes absolutely no sense to me; isn't the friction...

I am really confused as to how to determine the direction of friction acting on a rolling object. Could someone help clarify how to determine the direction of friction? ANy help is appreciated ;)

Homework Statement A cubical block of side L rests on a fixed cylindrical drum of radius R. Find the largest value of L for which the block is stable. This is problem 6.35 from the Kleppner+Kolenkow Introduction to Mechanics book. I honestly have no clue where to even start on this problem...

The reason I asked about tension is because I'm trying to solve the following problem(Kleppner 2.22): "A uniform rope of weight W hangs between two trees. The ends of the rope are the same height, and they each make angle thetha with the trees. Find: a. The tension at either end of the rope b...

thanks for the answers tim and Doc Al, it makes more sense now but if the tension force pulls both ends of a tiny element in opposite directions, wouldn't the net force on each tiny element be 0, and thus the net force on the rope be 0? please correct me if my reasoning is flawed

Is the direction of tension always tangent to the rope or thing for which it is acting? For example, let's say that there is a rope hanging with both ends on two trees at equal heights. THen the rope would form a parabolic shape. Would the tension, say, at the middle, then be directed...