Recent content by putongren

Here’s the full story. I am doing Physics questions on MIT OCW. They don’t post the answers to their problem set and I emailed them asking for the answers and they stated they don’t give out the answers. I just need help in determining whether my work is correct, so I choose to use PF for help.

OK, back from work. This is the sentence I meant to type: The gravitational acceleration of magnitude g is downward. You may neglect air resistance. Determine an expression for the initial height h from which the stone was dropped in terms of the constants A, B and g.

Sorry I was typing to question directly from the problem set and I typed the sentence wrong. I will retype that specific sentence when I get home.

Can you critique and offer suggestions on how I can get the correct value for h? I already offered my personal solution for it. Since you say it's wrong, then I need help in obtaining the correct solution.

Total Distance = distance traveled by stone + distance traveled by rocket. Total Distance = h Distance traveled by stone = xstone = (1/2)gt2 Distance traveled by rocket: arocket(t) = A - Bt vrocket(t) = At - (1/2)Bt2 xrocket(t) = (1/2)At2 - (1/6)Bt3 In order to find the maximum height of the...

Using Linear Algebra to solve this problem boggles the mind. Did you use matrices or vectors?

After thinking about the problem along with your helpful input, logically, the problem ends when the trains collide. d/2 = vt -> t = d/(2*v) Since "t" is the total time it takes for the problem to end, multiply “t” with u (bee’s velocity) to find the total distance the bee travels. Therefore...

This is a question from the MIT Open courseware website. (1). d = vt + ut let t = time it takes d = (u + v)t t = d / (u + v) (2). d = vt + ut d - vt = ut. Substitute t with d / (u + v) d - v*(d/(u+v)) = u*(d/(u+v)) d - v*(d/(u+v)) = “distance...

This question is from the MIT Courseware. I’m having difficulty finding the general equation to solve the problem (1). d = vt + ut d = (u + v)t t = d/(u + v) (2). d = vt + ut d - vt = ut sub t with d/(u+v) d - (v*d)/(u+v) = (u*d)/(u+v) I’m done with the...

I guess knowing the definition of an exact differential would help in answering my question: https://en.wikipedia.org/wiki/Exact_differential

I was researching about conservative and non-conservative forces, and there is some information in a website that sates that the work done is independent of path if the infinitesimal work 𝐹⃗ ⋅𝑑𝑟⃗ is an exact differential. It further states that in 2 dimensions the condition for 𝐹⃗ ⋅𝑑𝑟⃗ = Fxdx...

I'm just wondering, the charges are on the surface, and the electric field is inside the sphere. Does the charges qualify as in the same region as the region inside the sphere? The original question states that the charges has to be in the same region as the electric field.

How about a sphere with constant charge density on the surface? The electric field is 0 on the inside of the sphere, but there are charges on the surface.

This is a conceptual question. I think we can conclude that electric charges cannot be present if there is no electric field in that region. Is this an application of Gauss' Law? A net electric flux thru a surface indicates that there is a charge within that region. An electric field must be...

I understood the situation intuitively and conceptually concerning the equilibrium issue, but couldn't wrap my head around how the mathematics dictate whether the equilibrium is stable or not.