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# Help on M1 q. watch

1. A tug, of mass 9000kg, is pulling a boat, of mass 5000kg, by means of an inextensible string along a straight canal. The resistive forces opposing the motions of the tug and boat are 1500N and 800N respectively. Calculate, in N, the tension in the string when the tug is accelerating at 0.5ms^-2.
2. N2 on the system:

F - 1500 - 800 = (9000 + 5000)/2

=> F = 9300 N

N2 on the tug:

9300 - 1500 - T = 9000/2

=> T = 3300 N
3. wow...ppl here are so smart
4. Hehe

You didn't -really- need the first part of your working though...

Using N2L:
F = ma = 0.5 x 5000 --- (1)

Resultant force on boat: F = N - 800 --- (2)

Sub (2) -> (1):

N - 800 = 0.5 x 5000
.: N = (0.5 x 5000) + 800
.: N = 3300N

I think we've probably just been taught to do them differently though. Usually, we use the whole system to find the acceleration, then work on the individual segments (starting from the last attachment)... I love these questions!
5. (Original post by Aeroxyn)
You didn't -really- need the first part of your working though...
Your -technically- still doing what I'm doing, solving 2 equations in 2 unknowns.

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Updated: May 9, 2004
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