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# AS MECHANICS; Please explain how to work out these questions watch

1. http://s1116.photobucket.com/albums/...t=DSC_0002.jpg

a)0.3ms^-1
b)-0.1ms^-1
2. And what have you tried so far?
3. (Original post by Phenomenological)
And what have you tried so far?
All sorts of random things lol, but for one I know it's final velocity-initial velocity/time, so it would be 4/40=0.1ms^-1 but I don't really understand the difference between speed and velocity so I'm not sure which one that applies to and why...
4. (Original post by BuuTuu)
http://s1116.photobucket.com/albums/...t=DSC_0002.jpg

a)0.3ms^-1
b)-0.1ms^-1
a) From the graph, you can see that the lift goes up 4m, then down 8m. So average speed = distance/time = 12/40.

b) The displacement is the distance traveled in a given direction, in this case, 4m down. Velocity = Displacement/time.
5. (Original post by BuuTuu)
I don't really understand the difference between speed and velocity so I'm not sure which one that applies to and why...
Speed = distance covered per second in any direction
Velocity = distance covered per second in a particular direction

For example, if you run forwards 5 metres and then back 5 metres in two seconds, your average speed is 5 metres per second. But your average velocity is 0 because you are back where you started.
6. (Original post by BuuTuu)
http://s1116.photobucket.com/albums/...t=DSC_0002.jpg

a)0.3ms^-1
b)-0.1ms^-1
a) The question asks for the average speed so you need to do S = D/t
The graph shows displacement which is a vector quantity, Distance is a scalar.
Overall displacement is -4m but the distance covered is 12m so 12/4 =0.3ms^-1

b) This asks for the average velocity (which is a vector quantity) so you need to calculate Δs/t so -4/40 =0.1ms^-1

Hope this helps?
7. Velocity is a vector. Speed is a scalar.
8. (Original post by tom28)
a) From the graph, you can see that the lift goes up 4m, then down 8m. So average speed = distance/time = 12/40.

b) The displacement is the distance traveled in a given direction, in this case, 4m down. Velocity = Displacement/time.
thank you v.much
9. (Original post by Phenomenological)
Speed = distance covered per second in any direction
Velocity = distance covered per second in a particular direction

For example, if you run forwards 5 metres and then back 5 metres in two seconds, your average speed is 5 metres per second. But your average velocity is 0 because you are back where you started.
ohhh, ok I get it now thank you
10. (Original post by no1_titch)
a) The question asks for the average speed so you need to do S = D/t
The graph shows displacement which is a vector quantity, Distance is a scalar.
Overall displacement is -4m but the distance covered is 12m so 12/4 =0.3ms^-1

b) This asks for the average velocity (which is a vector quantity) so you need to calculate Δs/t so -4/40 =0.1ms^-1

Hope this helps?
It does thank you

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