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# Edexcel Physics Unit 1 17th May 2012

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1. (Original post by EllaBella<3)
Hey! Ugh, I hate these questions, I've only just got my read around them .. I really hope I don't mess up tomorrow!

The way that I go about this is to find the maximum height of the projectile. You should resolve the values you are given. Finding the maximum height, you use the VERTICAL components of the velocity.

Vv=3.5xsin70; this gives you 3.3ms^-1

From this, you now have three values you can plug into a kinematics in order to find a forth value.

V=3.3 U=0 (as the vertical velocity at the maximum height is zero) A=9.81 and you are trying to calculate S.

Using V^2=U^2 + 2as you can stick in your numbers, rearrange the equation and hopefully get the right answer!

Hope this helps - good luck tomorrow!

Heyy thankssss a toonnn!!! This is realllyyy clear! Step by stepp as i asked!!
It really did hellppp!!
And i hope luck stays with me tomorrow
Thanksss aloottttt once againnnn!!!
2. (Original post by LegendX)
Which of the following units is equivalent to the SI unit for energy?

Kgms-2
KwH
Nm-1
Ws

Is there any quick way of doing this?
Ok these are always just based on common formulae, ill go through each step by step:

Kg ms-2 - this is a mass times an acceleration, ring any bells? Of course its force (F=ma)

KwH - This is a cheeky one because it IS unit for energy but NOT SI UNIT. Kw is power so is equivalent to work done over time, In this case Kilojoules/seconds. Hour is time too so cancels giving Kilojoules alone.

Nm-1 - this is your stiffness unit from k=f/x

Ws - this is it! Like KwH it is a power (j/s) timed by time (s) giving SI unit Joules

Hope that helps - just process of elimination!

S
3. (Original post by LegendX)
Which of the following units is equivalent to the SI unit for energy?

Kgms-2
KwH
Nm-1
Ws

Is there any quick way of doing this?
Funny you ask this, I was doing it today only MCQ I stumbled over I got it right but through process of elimination which ain't good

So you know energy is always given in Joules

which of those units are equivalent to J

Well, it's the last one

Power = work done/time which is Js-1

Js-1 can also be called a Watt (W) ... don't forget there was an S after W

Js-1 x S .. two S's cancel out youre left with Joules

Hope you got it
4. Ah thanks guys, btw turbulence is caused by high speeds r anything that disrupts the Laminar flow? If s what could the factors that disrupt be?
5. Can any body help me out with this mcq..in january 2009..number 10..
a freely falling object on earth has a speed of 5.0 ms^-1
After Falling a further 20 m its speed is ??
the answer is 20ms^-1 but howw?
6. (Original post by LegendX)
Ah thanks guys, btw turbulence is caused by high speeds r anything that disrupts the Laminar flow? If s what could the factors that disrupt be?
turbelence occurs at higher speeds....i dont think there are any other factors
7. (Original post by GreeseMonkey)
Can any body help me out with this mcq..in january 2009..number 10..
a freely falling object on earth has a speed of 5.0 ms^-1
After Falling a further 20 m its speed is ??
the answer is 20ms^-1 but howw?
u=5
a=-9.8
s=-20(because its falling down)
use v^2=u^2+2gs
8. (Original post by GreeseMonkey)
Can any body help me out with this mcq..in january 2009..number 10..
a freely falling object on earth has a speed of 5.0 ms^-1
After Falling a further 20 m its speed is ??
the answer is 20ms^-1 but howw?
v^2 = u^2 + 2as

s = 20m
u = 5ms^-1
a = 9.81ms^-2

sub everything in and you should get 20ms^-1 =]
9. (Original post by youlostme)
u=5
a=-9.8
s=-20(because its falling down)
use v^2=u^2+2gs
Thanks ALOT!
10. (Original post by Zues)
v^2 = u^2 + 2as

s = 20m
u = 5ms^-1
a = 9.81ms^-2

sub everything in and you should get 20ms^-1 =]
THANKS!!!!!
11. (Original post by GreeseMonkey)
THANKS!!!!!
No worries =]

First exam for me and this exam is a retake for me. Gone through all the past papers and now I'm just looking through here to get me into exam mood.
12. Right I'm signing off, I'd recommend anyone else to do the same! Revising is only useful up the point where sleep needs to take over! Good luck in the morning everyone, I look forward to the discussions and controversy that will surely ensue at midnight tomorrow..

S
13. (Original post by Salmonidae)
Right I'm signing off, I'd recommend anyone else to do the same! Revising is only useful up the point where sleep needs to take over! Good luck in the morning everyone, I look forward to the discussions and controversy that will surely ensue at midnight tomorrow..
Amen.
14. yeah im going to sign off too
goodluck people! we shalt meet again after 24 hours =P i just hope we wont be discussing how dreadful the paper was....
15. Can somebody please explain why the answer to this question is 'b'.

16. What do you think it is?
17. guys theres this question about springs which is often repeated..
A spring extends by 10cm when a force of 8N is applied..the limit of proportionality is not exceeded..two of these springs are arranged side by side and a force of 4.0N is applied
the extension for this arangement of springs is?
anser is 2.5
can u guys help me out with this
18. (Original post by Zues)
No worries =]

First exam for me and this exam is a retake for me. Gone through all the past papers and now I'm just looking through here to get me into exam mood.
lol im going through the pastpapers atm
19. (Original post by GreeseMonkey)
guys theres this question about springs which is often repeated..
A spring extends by 10cm when a force of 8N is applied..the limit of proportionality is not exceeded..two of these springs are arranged side by side and a force of 4.0N is applied
the extension for this arangement of springs is?
anser is 2.5
can u guys help me out with this
If the two springs are next to eachother, then the force that is applied will be shared between them. 4N on one spring would give extension of 5cm. Since there are two springs, the force on each spring would be 2N, which gives extension 2.5cm.
20. (Original post by Zues)
If the two springs are next to eachother, then the force that is applied will be shared between them. 4N on one spring would give extension of 5cm. Since there are two springs, the force on each spring would be 2N, which gives extension 2.5cm.
Can you please explain me my question in post#195.

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