Recent content by fchen720

I'm face palming right now... Thank you so much.

Homework Statement Please see attached picture. Homework Equations Shown in picture The Attempt at a Solution It's a textbook example that has a solution. At the middle right hand side of the picture, they say "From Eq... Vcm = Rw" (Where 'cm' is centre of mass) I don't understand why this is...

Thank you so much TSny, I understand now!

Sorry for being slow but I don't quite understand. Why is the left pointing blue force acting on the massless block? It seems to me that the left pointing green reaction force is the only force acting directly on the block, and the horizontal force acting on Brian F=60A equals the reaction...

Ok, but I don't understand why the solution has p = (60 + 80)a when gravity is responsible for the movement of John and the force is only applied to Brian. Shouldn't it be p = 60a?

Homework Statement The problem and solution are attached, but I don't think the solution is correct. Homework Equations The Attempt at a Solution The only thing I don't understand is why Joe needs to supply the force to move both people. It seems to me that gravity is providing...

Ok nevermind I understand now.

:redface: Thanks for pointing that out, but I'm still confused. Since the missile must travel to latitude 45 doesn't it spend time not gaining as much ground as it potentially could compared to if it were on latitude 45 during the entire 10 minutes (but at the higher speed)?

Homework Statement The problem and solution involving the ballistic missile question is in the attached picture. Homework Equations The Attempt at a Solution Why does the first expression have (24)(6) in the denominator, when the second expression has (24)(6)(2) ? My thought...

Thank you for replying Lewando. Much appreciated!

My problem with the question is that I shouldn't be able to move both boxes by applying 1.5umg. Maybe the average force is 1.5umg as I'm stretching the spring, but shouldn't I eventually need to apply 2umg for the spring to fully stretch? If I'm correct, the answer should be 2umg.

Homework Statement Both the question and solution are on this link (Question 7): http://sin.uwaterloo.ca/solutions_2012.pdf I understand the solution they provided, but I think the question is misleading and should not have been worded that way. I just want to clarify if I'm right or not...

Thanks for all the replies.:smile: Yesterday I got the parts, put the radio together and success! I could actually hear a few radio stations. The sound was barely audible, and everyone had to be quiet if we wanted to hear anything. I'm not sure if that's the norm with crystal radios though...

Homework Statement I'm in grade 11 working on a science fair project I found on this site: http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_p014.shtml Grade 11 physics doesn't cover much so I'm confused about why the radio is set up the way it is... I know that...

Thanks to everyone who answered.