- #1
Lolagoeslala
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Homework Statement
Garfield (a cat) and John (his human) did not go to the Olympics (not feline up to
it). However, they got in trouble. John sits on a frictionless skateboard on a
horizontal parking lot. A light strong rope tied to a solid post passes horizontally
to the skate board, passes around a pulley on the skateboard, returns horizontally
to pass above the post, around a second pulley and vertically down into a yawning
chasm. Garfield hangs on tightly to the bottom end of the rope. Garfield has a
mass of 20 kg (too much lasagna), John and the skateboard have a combined mass
of 60 kg. Calculate the tension in the rope before John hits the post or Garfield
bottoms out.
The Attempt at a Solution
My FBD diagrams
http://s1176.beta.photobucket.com/user/LolaGoesLala/media/c_zps40e98e7e.png.html
Ok so this is what i came up with to find the tensin between the cat and the by and skateboard
m
Fnet = Fg - T
ma = md - T
M
Fnet = Fg + Fn + T
Fnet = T
Ma = T
Combining
a = (mg/m+M)
To find the tension
Ma = T
M(mg/m+M) = T
T = (M x m/M +m)g
T = ( 60000g x 20000g/60000g + 20000g)(9.8m/s^2)
T = 147000N
so that is the tension between john/skateboard and the cat
however how do i account for the nail and the tension between john/skateboard and the nail ?
Here is a rough sketch of what i think it looks like
http://s1176.beta.photobucket.com/user/LolaGoesLala/media/f_zpsafd5a9e3.png.html