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# Current Year 13 Thread (2013/14) - Mark I Watch

1. (Original post by Qari)
I have bunked lessons. My parents wouldn't dare let me bunk school.

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I don't think I've done that actually. I have a few med conditions that flare up, so I just use that as an excuse sometimes (once I really was actually ill though)

(Original post by Blueray2)
I bunked my free periods
How do you bunk frees? Haha
(Original post by lilGem)
It is CHE/PHA are minutes from where I live
That's pretty cool I know someone doing geography there
2. Had Physics exam last week. Lost 6 marks due to answers. When I retyped on my calculator I got the right answer but first time I got different. Anyone know why?

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3. (Original post by Endless Blue)
Argh, thanks, that was really simple. I'm stuck on the next question though...

Q) Albert and Bella are standing in a lift. The mass of the lift is 250kg. As the lift moves upward with constant acceleration, the floor of the lift exerts forces of magnitude 678N and 452N respectively on Albert and Bella. The tension in the cable at the which is pulling the lift upwards is 3995N.

a) Find the acceleration of the lift.
b) Find both Albert's and Bella's mass.

I really am clueless on this question. I know it's F=ma but no idea where to go with finding the acceleration, as I can't work out the resultant force
Ah everyone loves lifts.

By Newton's law, the force exerted on the person by the floor is equal to the force exerted on the floor by the person. So consider the lift only and use that to work out a. It's hard to explain, sorry, but see if you can get what I'm saying...if not, post your working and I'll have a look.
4. (Original post by mynameisntbobk)
That's pretty cool I know someone doing geography there
It is a brilliant university, so glad I came here
5. (Original post by Endless Blue)
Yes. I thought that, but what you've got there is wrong (I had it too). The answer is 1.5ms^-2.
Oh no! I remember when I was doing lifts it was always hit and miss
6. (Original post by lilGem)
It is a brilliant university, so glad I came here
Even over Exeter?
7. (Original post by usycool1)
Ah everyone loves lifts.
On first glance I thought that said "everyone loves tits" XD.
8. (Original post by Dilzo999)
On first glance I thought that said "everyone loves tits" XD.

9. (Original post by mynameisntbobk)
Even over Exeter?
10. (Original post by lilGem)

Aww, then I'm really happy for you
11. (Original post by usycool1)
Ah everyone loves lifts.

By Newton's law, the force exerted on the person by the floor is equal to the force exerted on the floor by the person. So consider the lift only and use that to work out a. It's hard to explain, sorry, but see if you can get what I'm saying...if not, post your working and I'll have a look.
Hmm. Okay, so I'm still confused, sorry. So I'm just considering the lift? But then all I have is 3955 - T* = 250a. So in my working I have two unknowns..

I understand your explanation for b, but don't understand a. Sorry
* T = downward force

(Original post by Robbie242)
Any ideas?
12. (Original post by Endless Blue)
Hmm. Okay, so I'm still confused, sorry. So I'm just considering the lift? But then all I have is 3955 - T* = 250a. So in my working I have two unknowns..

I understand your explanation for b, but don't understand a. Sorry
* T = downward force
F = ma

So f has to equal 375 right? Where could we get that from.... Hmm... Sorry, I should be able to help but minds on Twitter
13. (Original post by L'Evil Fish)
F = ma

So f has to equal 375 right? Where could we get that from.... Hmm... Sorry, I should be able to help but minds on Twitter
I know! I hope Usy can help me out..
14. (Original post by Endless Blue)
I know! I hope Usy can help me out..
I cba getting paper and drawing a diagram, I feel bad. There's an examsolutions video for lifts
15. (Original post by mynameisntbobk)
I don't think I've done that actually. I have a few med conditions that flare up, so I just use that as an excuse sometimes (once I really was actually ill though)

How do you bunk frees? Haha

That's pretty cool I know someone doing geography there
Was just saying it as a joke
16. (Original post by Endless Blue)
Argh, thanks, that was really simple. I'm stuck on the next question though...

Q) Albert and Bella are standing in a lift. The mass of the lift is 250kg. As the lift moves upward with constant acceleration, the floor of the lift exerts forces of magnitude 678N and 452N respectively on Albert and Bella. The tension in the cable at the which is pulling the lift upwards is 3995N.

a) Find the acceleration of the lift.
b) Find both Albert's and Bella's mass.

I really am clueless on this question. I know it's F=ma but no idea where to go with finding the acceleration, as I can't work out the resultant force
Let be Albert's mass and be Bella's mass and the acceleration on the lift be . As a force of is exerted on Albert then . Similarly, .

Now, considering the lift:

.

Substitute and into .

Edit: Also, did you make a typo and should the tension in the cable of the lift be 3955 N?
17. A2 Physics what you learning.

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18. (Original post by Endless Blue)
Could anyone offer any M1 help?

Q) The engine of a van of mass 400kg cuts out when it is moving along a straight horizontal road with speed 16m/s. The van comes to rest without the brakes being applied. Assume the resistive force against the van to be 200N.

a) find how long it takes the van to stop.
b) find how far the van travels before it stops.
c) comment on the suitability of the modelling assumption.

Is this suvat? I'm really confused about a) and b).
I think youre probably wanted to consider energy changes...but if you haven't covered that then I imagine SUVAT yes
19. (Original post by Qari)
Had Physics exam last week. Lost 6 marks due to answers. When I retyped on my calculator I got the right answer but first time I got different. Anyone know why?

Posted from TSR Mobile
Radians/ degrees problems? This gets me sometimes

http://www.thestudentroom.co.uk/show....php?t=2488481

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