This discussion is now closed.

Check out other Related discussions

Friction question..M1

4

I have this Friction question that I cant seem to work out...

A loaded crate of mass 80kg is to be moved along rough horizontal ground. A student was asked to compare the least 'pushing' force needed with the least 'pulling' force needed. The student modelled the crate as a particle, and looked at this problem by considering only 'pushing' forces and 'pulling' forces inclined at 30° to the horizontal. In a diagram the least 'pushing' force has magnitude X newtons. Given that the coefficient of friction between the crate and the ground is 0.6, find X.

Thanks alot
From John

Reply 1

7589200

18

Sorry, im unsure as to what you mean by pushing and pulling forces.

There is: mg sin 30 acting down the slope, this is 40g. There is 24g rt3 of friction and there is X. Try resolving these.

Reply 2

zrancis

2

Hmm, I dont seem to be gettin around to 831, are you sure all the info is right?

Reply 3

Neo1

OP

4

Well basically there's a diagram, which is a particle resting in a horizontal plane, and a force at 30° pushing down on the particle....

Any help..

The answer is meant to be 831N.

Thanks a lot
From John

Reply 4

zrancis

2

My bad,

Res vert: R = 80g

As F = mu(R)

Reply 5

steve2005

17

Neo1

I have this Friction question that I cant seem to work out...

A loaded crate of mass 80kg is to be moved along rough horizontal ground. A student was asked to compare the least 'pushing' force needed with the least 'pulling' force needed. The student modelled the crate as a particle, and looked at this problem by considering only 'pushing' forces and 'pulling' forces inclined at 30° to the horizontal. In a diagram the least 'pushing' force has magnitude X newtons. Given that the coefficient of friction between the crate and the ground is 0.6, find X.

Thanks alot
From John

I suggest do a diagram, possibly in Excel, and upload.

Sample diagram.xls8.2KB

Reply 6

Neo1

OP

4

Diagram attached:

Thanks
From John

Diagram.JPG5.6KB

Reply 7

zrancis

2

Are you positive its 831?

Resolve horiz:

Friction < Xcos30
mu(R) < X[(sqrt(3))/2]

Res vert:

R = mg
R = 80g

80g(0.6) < X[(sqrt(3))/2]
X > 32g(sqrt(3))
X > 542.17
For X to move the particle, it must be greater than 542N

Reply 8

steve2005

17

Neo1

Well basically there's a diagram, which is a particle resting in a horizontal plane, and a force at 30° pushing down on the particle....

Any help..

The answer is meant to be 831N.

I get 831N

Picture 5.png32.3KB

Reply 9

zrancis

2

Haha, very straightforward.

I managed to get myself a reputation a college for not being able to work out the force exerted on a particle by the plane, how cool am I.

cheers for sorting that steve. I can go to sleep now

Reply 10

generalebriety

16

zrancis

Haha, very straightforward.

I managed to get myself a reputation a college for not being able to work out the force exerted on a particle by the plane, how cool am I.

cheers for sorting that steve. I can go to sleep now

That's one hell of a reputation. "Hey look, it's I-can't-work-out-the-force-exerted-on-a-particle-boy!"

Reply 11

zrancis

2

generalebriety

That's one hell of a reputation. "Hey look, it's I-can't-work-out-the-force-exerted-on-a-particle-boy!"

And how it hurts me for you to say something like that :biggrin:

The tears always come flooding back at night.

Friction question..M1

Related discussions

Articles for you