The discussion revolves around a physics problem related to total kinetic energy, specifically within the context of mechanical energy conservation. Participants are analyzing various aspects of energy transformations and the implications of gravitational work in a system involving multiple masses.
The discussion is active, with participants sharing their calculations and reasoning. Some have received guidance on refining their approaches, particularly regarding the interpretation of gravitational work and energy conservation principles. Multiple interpretations of the problems are being explored without a clear consensus.
Participants are navigating constraints such as the specifics of the exam problems and the assumptions about energy conservation in the presence of external forces. There is an ongoing debate about the directionality of work done by gravity and its implications for energy calculations.
This is an equilibrium problem: no need for rotational inertia or energy methods. Hint: What must be the net torque on the cylinder?Alt+F4 said:
Two reasons:Alt+F4 said:
Okay SoDoc Al said:
i know the sum of torques should add up to zero. so t= F*L t = F * 80. i have no idea any more hints. I did 15*9.8*50 / ( 80) and got the answer don't know if that was luck or i actually understood itDoc Al said:
(2)(9.8)(sin41) is correct for the component of gravity down the incline, but (.27)(2)(9.8) is not correct for the friction force. (Remember that F_f = \mu N.)Alt+F4 said:
That's all there is to it. The hanging mass exerts a counter-clockwise torque on the cylinder; the force on the handle exerts a clockwise torque. These must be equal (and opposite) for rotational equilibrium.Alt+F4 said:
What you're doing wrong is jumping the gun and not reading the question. You immediately went to solve for the support force, but that was not the question.Alt+F4 said:
Yes, that's how it's done.Alt+F4 said:
Thanks. Okay so 3 forces acting on car, Inward centripetal, normal and Gravity. Centripetal Acc = 7.5 m/s^2 how do i find friction thanks"centripetal" is a direction, not a kind of force. The three forces are: friction, normal force (what is that?), and weight.Alt+F4 said:http://online.physics.uiuc.edu/cgi/courses/shell/phys101/spring06/prep2a.pl?practice/exam1/sp05 Question 19. My exam is in 2 hrs so can i have strong hints.
Hint: What must be the same about the two wheels, since the belt doesn't slip?Alt+F4 said:
ooo man i am so stupid. I wish i had hints like these durin exams hahaa i was making it more complicated than it is. thanksDoc Al said:
You have all the info needed to figure out T_1 & T_2.Alt+F4 said:
I assume you're talking about problem 4. Don't confuse force with torque. Hints: What is \alpha? (Key: rolling without slipping.) What force produces the torque about the center of mass?Alt+F4 said:
One way to solve this is to use conservation of energy. Hint: Realize that the cylinder will have both rotational and translational KE. (The two are related, since it rolls without slipping.)
thanks for all ur help