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A level mechanics- Resolving forces

I'm confused about what to do on a revision question, it is slightly different to typical resolving forces as no angles are given.. here it is:

A crate is being pulled at a constant speed across a rough horizontal ground by a rope. The crate is of weight 100N and the frictional force between the crate and the ground is of magnitude 30N. The tension in the rope is of magnitude T newtons.
The coefficient of friction between the crate and the ground is 0.5.

I have worked out the normal reaction force to be 60N.

The question asks me to find the value of T, and also the angle that the rope makes with the horizontal.

I have resolved horizontally and vertically,
horizontally:
30 = Tcosx
Vertically:
60 + Tsinx = 100
and i have tried rearranging and substituting in, but i can't work it out :s-smilie:

any help? :smile:
thanks! x
Original post by amyvickers
A crate is being pulled at a constant speed across a rough horizontal ground by a rope. The crate is of weight 100N and the frictional force between the crate and the ground is of magnitude 30N. The tension in the rope is of magnitude T newtons.
The coefficient of friction between the crate and the ground is 0.5.

The question asks me to find the value of T, and also the angle that the rope makes with the horizontal.


Can you type out the exact wording of the question please? Since I have a feeling you may have overlooked something.. then I may be able to help :h:
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bcrazy
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Original post by amyvickers
I'm confused about what to do on a revision question, it is slightly different to typical resolving forces as no angles are given.. here it is:

A crate is being pulled at a constant speed across a rough horizontal ground by a rope. The crate is of weight 100N and the frictional force between the crate and the ground is of magnitude 30N. The tension in the rope is of magnitude T newtons.
The coefficient of friction between the crate and the ground is 0.5.

I have worked out the normal reaction force to be 60N.

The question asks me to find the value of T, and also the angle that the rope makes with the horizontal.

I have resolved horizontally and vertically,
horizontally:
30 = Tcosx
Vertically:
60 + Tsinx = 100
and i have tried rearranging and substituting in, but i can't work it out :s-smilie:

any help? :smile:
thanks! x


The vertical equation gives Tsinx=40 (call this Equation 1)
Horizontal had given Tcosx=30 (Equation 2)

Doing Eq1 divided by Eq2 will give tanx=4/3 and then you can solve...

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