Ok, ok, so I WASN'T thinking clearly. We want to know when the U_el EQUALS U_grav (less the energy lost to friction). I was sillily removing energy from the equation when I was subtracting the work done by gravity.
So, U_el = F_frict(x meters) + U_grav
or
54.7J = x(2.36N+13.57N) -> x =...
Okay - still getting a wrong answer. It's because I'm approaching it the wrong way, I know, but wanted to clue you into my thought process here.
So, we have 54.7J of potential elastic energy sitting down there and we want to find out how high up that box gets when the elastic energy is...
Homework Statement
A 1.71 kg package is released on a 54.1 deg incline, 4.00m from a long spring with force constant 141 N/m that is attached at the bottom of the incline . The coefficients of friction between the package and the incline are 0.39 and 0.24. The mass of the spring is...
i knew it was something simple i was missing in substitution - if you say
T_2 = T_1 + 1/2m_pulley(a)
then
T_1 + 1/2m_pulley(a) = m_2(g-a)
then
T_1 = m_2(g) - (1/2m_pulley + m_2)a
then
m_2(g) - (1/2m_pulley + m_2)a = m_1(a-g)
and we get values
Thanks very much.
For anyone else...
got sloppy and used the N instead of the kg for the inertia. right. so i get T_2 - T_1 = Ia/r
or .715kgm(a). I'm still staring at three variables and my eyes are starting to bleed.
T_2 - T_1 = .715kgm(a)
7.653kg(a) = T_1 - 75N
12.755(a) = 125N - T_2
sure, let's factor out a and get...
Homework Statement
Two weights, 75N (mass 1) & 125N (mass 2) are connected by a very light flexible cord that passes over a 70.0 N frictionless pulley of radius 0.200 m. The pulley is a solid uniform disk and is supported by a hook connected to the ceiling. What force does the ceiling exert...
I guess I'm having trouble visualizing the forces, which is frustrating as I knocked projectile motion and angular acceleration and all that on its butt in our last section.
I keep picturing Block B with a downward force of 147N and the rope pulling up towards the pulley, down the incline...
Homework Statement
A block with mass 10.7 kg is placed on an inclined plane with slope angle 24^\circ and is connected to a second hanging block that has mass 15 kg by a cord passing over a small, frictionless pulley. The coefficient of static friction is 0.47 and the coefficient of kinetic...