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# M3: angular vs linear volcity watch

1. what does he mean by the different equation for a: angular and linear? r(w^2) is angular and (v^2)/r is linear.
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2. also, how are you to differentiate between the horizontal force acting towards the centre and which force is pushing the particle away?

here, R sin(a) provides force acting towards the centre.
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3. (Original post by Maths&physics)
what does he mean by the different equation for a: angular and linear? r(w^2) is angular and (v^2)/r is linear.
For the first question, the angular velocity is the rate at which you are moving with respect to the angles. So it would be angles turned per second.
Linear velocity is the speed you are moving at with respect to distance. In metres per second (metres along the circumferance of the circle you cover every second)
4. (Original post by Maths&physics)
also, how are you to differentiate between the horizontal force acting towards the centre and which force is pushing the particle away?

here, R sin(a) provides force acting towards the centre.
i dont understand what is happening in the second question, is the particle resting on the slope or is it moving perpendicular to the slope? and is it related to the first question?
5. (Original post by BlobBlob69)
i dont understand what is happening in the second question, is the particle resting on the slope or is it moving perpendicular to the slope? and is it related to the first question?
its the same topic as the first question. its a particle performing horizontal circles on a banked track.
6. (Original post by Maths&physics)
its the same topic as the first question. its a particle performing horizontal circles on a banked track.
O right, forces acting towards the center would be the contact force between the car and road, resolved in that direction. The weight of the car which pulls it down into the slope.

Acting outwards would be the centrifugal force due to the rotation.

the question should indicate which direction friction is directed in. Because it could be acting towards the centre if it were a small slope ad fast speed so you could see it as the car is about to skid away from the center without friction. OR if the slope is great and the car is moving slow, friction could be stopping the car from sliding into the centre, so check the question.
7. (Original post by BlobBlob69)
O right, forces acting towards the center would be the contact force between the car and road, resolved in that direction. The weight of the car which pulls it down into the slope.

Acting outwards would be the centrifugal force due to the rotation.

the question should indicate which direction friction is directed in. Because it could be acting towards the centre if it were a small slope ad fast speed so you could see it as the car is about to skid away from the center without friction. OR if the slope is great and the car is moving slow, friction could be stopping the car from sliding into the centre, so check the question.
its a smooth surface, but force R (due to gravity) is acting towards the centre apparently, even though he drew the arrow facing outwards?!

he goes on to say that the driving force of the car is the force acting out, which makes sense but how can gravity (a force acting down) be the force acting towards the centre?
8. is the car travelling like 1 or 2, or neither?
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9. (Original post by RDKGames)
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10. Hi there, sorry i forgot about this post. If your still doing the problem could you post the full question so i can better understand whats going on and solve it once and for all lol
11. (Original post by BlobBlob69)
Hi there, sorry i forgot about this post. If your still doing the problem could you post the full question so i can better understand whats going on and solve it once and for all lol
so for this question, both R and the speed at will the particle are travelling are forces acting towards the centre. as there is no friction, what is keeping the particle from not traveling towards the centre.

also, viewing the banked track as a velodrome helped a lot! this east explained in the tutorial.
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12. Ok so this is a circular motion question and we are being asked of the angular velocity (w) so we are going to need either:

v=rw or a=rw2

we don’t know v so we are going to use the other one. a=rw2 but we don’t know the acceleration, however we can work it out

We know that f=ma so we can re write the equation as a=f/m and substitute it in. now we have:

f/m=rw2

r can be calculated using trig shown on the diagram

f can be also found
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13. well thats the method anyway, be sure to check the math if theres any mistakes
14. (Original post by BlobBlob69)
Ok so this is a circular motion question and we are being asked of the angular velocity (w) so we are going to need either:

v=rw or a=rw2

we don’t know v so we are going to use the other one. a=rw2 but we don’t know the acceleration, however we can work it out

We know that f=ma so we can re write the equation as a=f/m and substitute it in. now we have:

f/m=rw2

r can be calculated using trig shown on the diagram

f can be also found
thanks

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