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Q: A bulldozer drags a log weighing 400 N along a rough surface. The cable attac

ID: 1259790 • Letter: Q

Question

Q: A bulldozer drags a log weighing 400 N along a rough surface. The cable attached to the log makes an angle of 20.0 degrees with the ground. The coefficient of static friction between the log and the ground is 0.400. What minimum tension is required in the cable in order for the log to begin to move?

I have drawn this out and looked it up. There is a very similar question here on Chegg, but it does not seem that it was answered adequately - the main comment insisted that the vertical component was not taken into consideration.

This is the image of what I have done so far, sorry it's a little messy:

I would be grateful for help.

Q: A bulldozer drags a log weighing 400 N along a rough surface. The cable attached to the log makes an angle of 20.0 degrees with the ground. The coefficient of static friction between the log and the ground is 0.400. What minimum tension is required in the cable in order for the log to begin to move? I have drawn this out and looked it up. There is a very similar question here on Chegg, but it does not seem that it was answered adequately - the main comment insisted that the vertical component was not taken into consideration. This is the image of what I have done so far, sorry it's a little messy: I would be grateful for help.

Explanation / Answer

Let:
T = tension on the cable.
N = normal force
Ff = force of friction

N = 400 - T sin20

Ff = 0.4 N = 0.4(400 - 0.342T) = 160 - 0.1368T

Ff = Tcos 20

160 -0.1368T = 0.9396T

1.0764T = 160

T = 148.64N