# Thread: Mechanics last minute help

1. ## Mechanics last minute help

Hi.

Not sure if this is a stupid question or not ...

When drawing a free body diagram in a banked track question (question doesn't provide it), how do we know which direction to draw the lateral force (up or down the slope), as wouldn't the direction affect the result when we resolve the horizontal and vertical forces?

Thanks

2. ## Re: Mechanics last minute help

Originally Posted by Cryptical
Hi.

Not sure if this is a stupid question or not ...

When drawing a free body diagram in a banked track question (question doesn't provide it), how do we know which direction to draw the lateral force (up or down the slope), as wouldn't the direction affect the result when we resolve the horizontal and vertical forces?

Thanks
Well I'm pretty sure the question would say slide up or down the track. If its slide down then the force is up the slope and vice versa..

3. ## Re: Mechanics last minute help

Originally Posted by Cryptical
When drawing a free body diagram in a banked track question (question doesn't provide it), how do we know which direction to draw the lateral force (up or down the slope)
I'm pretty sure you wouldn't be able to know.

The direction of the lateral force is dependent on the speed of the body in relation to the design speed of the track.

HSC questions should always (and they have) provide a diagram for this sort of question.

4. ## Re: Mechanics last minute help

Originally Posted by fan96
I'm pretty sure you wouldn't be able to know.

The direction of the lateral force is dependent on the speed of the body in relation to the design speed of the track.

HSC questions should always (and they have) provide a diagram for this sort of question.
According to my sources if the thing is travelling faster than the optimal speed it will slide up the track and below optimal it will slide down. Using this you should be able to tell which way friction is pointing.

5. ## Re: Mechanics last minute help

Originally Posted by Drdusk
According to my sources if the thing is travelling faster than the optimal speed it will slide up the track and below optimal it will slide down. Using this you should be able to tell which way friction is pointing.
Only if the speed of the body is given to you...

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