Edexcel PHYSICS Doubts

[astarmathsandphysics]

Is this m2?

[astarmathsandphysics]

answered. Too complicated for A level physics i think.

[dk bose]

no,its is a thinking task from the first section of the Edexcel A2 physics study guide.

[dk bose]

A ceiling fan is turning at a rate of 100 revolutions per minute. A spider is clinging to a blade of the fan. If the spider experiences a centripetal acceleration greater than 0.3g, it will lose its grip on the blade and be flung
off. How far from the centre of the fan can the spider safely go?

one more tough questions,solve it if u can??

[The Golden Girl =D]

URGENT HELP NEEDED!

Whoever can help PLEASE HELP !

I have an exam tomorrow and I need someone to explain to me why I got my answers wrong.

I got 2/10 in the June 2011 Section A  

ALL Question in Section A EXCLUDING Q.5 and 10.


so Please help !

Attached.

[astarmathsandphysics]

A ceiling fan is turning at a rate of 100 revolutions per minute. A spider is clinging to a blade of the fan. If the spider experiences a centripetal acceleration greater than 0.3g, it will lose its grip on the blade and be flung
off. How far from the centre of the fan can the spider safely go?
need to know mass of s[ider

[astarmathsandphysics]

sorry misread question
a=v^2/r ==(2 pi r f)^2/r =4 pi^2 f^2 r =0.3g so r=0.3g/(4 pi^2 f^2)=2.94/(4 pi^2 *(100/60)^2) = 0.026 m

[astarmathsandphysics]

Whoever can help PLEASE HELP !

I have an exam tomorrow and I need someone to explain to me why I got my answers wrong.

I got 2/10 in the June 2011 Section A         

ALL Question in Section A EXCLUDING Q.5 and 10.


so Please help !
 lokking now

[astarmathsandphysics]

jun 11 answers
1. D since f=ma=m dv/dt= d(mv)/dt= rate of change of momentum. F is equal to the weight.
2. A applying the left hand rule around the loop shows the force always inwards
3. C s since time in seconds
4.C flux linkage is BAN =0.002*0.0004*50
5. D. since gravity mg acts down and centrifugal force=mv^2/r acts up
6. B lenz's law - if the switch is opened the current is Y decreases so the current in X increases to maintain the current in Y
7.mv^2/r=Bev so v=Ber/m=0.02*1.6*10^-19*1.5/(1.67*10^-27)=2.9*10^6 B

[The Golden Girl =D]

Sir I have more Questions , do u have the time to answer me 

[The Golden Girl =D]

I really hope you answer me 

Same paper :

Q.8 and Q.9... as well as Q]12)b)  [ I never seem to understand these graphs ] .. Q.14  [ didn't get the MS at all :$ ]  ..Q.17]c)iv)

I guess that's all 

[astarmathsandphysics]

8.C since the rest mass of a positron is 9.1*10^-31 kg
9.1.8*10^-29 kg
1Mev/c^2=1*10^6*1.6*10^-19/(3*10^8)^2 =1.8*10^-30 kg

(1.8*10^-29)/1.8*10^-30=10 A
10 C since E=mc^2

[The Golden Girl =D]

but Sir , 8 is B according to the MS :$

and 9 the answer of nine isn't within the option of A to D :S

[astarmathsandphysics]

12. take logs
ln (R)=ln(R_0) - ut
-u is gradient = (3.26-4.28)/(24-8)=-1.02/16=-0.06375/cm
14. Between the plates the field E is constant so the force on the charged ball is F=Eq and acceleration is a=F/m=Eq/m also constant (so v is a straight line). When the ball its a plate is is charged with opposite sign so is repelled from plates but as before, acceleration constant.

[astarmathsandphysics]

Of course 8 is B I thought is said travelling at relativistic speed.