- #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