Help please......

[danfriday92]

hey guys, I got problem with physics q13,18,19,21,37 o/n 2010 paper 11

thanks in advance.........

 

[workinghard]

let me tak a look!
i ll pm u soon
lites gonna go in afew short min!

 

[libra94]

Q13...moments is the product of force and the perpendicular distance between the force and the pivot
moments in clockwise directions are....(5*2)+(10*2)=30Nm (always remeber to take the perpendicular distance!!)
moments in anticlockwise direction is...15*3=45Nm
so the resultant will be 45-30= 15Nm

 

[libra94]

Q18......as the masses are pulled by the gravitational force and they are rising i.e gaining G.P.E.
we use the gravitational potential energy..mgh
the weight of the elevator is conterbalanced by m2 so to cancel its effect we subtract m2 frm m1
so its D

 

[libra94]

Q19...pressure in liquids is..ρgh
where ρ is the density, g is the gravitational acceleration that is 9.81ms-2 and h is the depth frm the surface
p=ρgh
=1020*9.81*(10*1000)=100 062 000 Pa which is apprx. equal to 10^8 Pa

 

[libra94]

energy stored in the sring is the area under the curve
i.e. the area under the curve frm 0 till 30mm..the area of a triangle
area...1/2*6.3*(30/1000)=0.095 J

make sure that u convert the units!!!

 

[libra94]

the amt of voltage passing throught the potentiometer is the same whether the slider is at X or at Y
so its A.

 

[workinghard]

29 C
curved path always n since da field lines are directed downwards its +ive plate on the upper side and so e ll move towards +ive plate!

 

[workinghard]

oopsi i misread da ques sorry

 

[danfriday92]

29 C
curved path always n since da field lines are directed downwards its +ive plate on the upper side and so e ll move towards +ive plate!

actually the answer is D but thanks anyway.....

that aside, what does the answer means by part of cicle & not part of circle?

thanks in advance......

 

[workinghard]

29 C
curved path always n since da field lines are directed downwards its +ive plate on the upper side and so e ll move towards +ive plate!

actually the answer is D but thanks anyway.....

that aside, what does the answer means by part of cicle & not part of circle?

thanks in advance......

no sir it IS C!
i jst rechecked!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :!:
part of a circle or not part of circle refers to the direction it follows
ie it can either go in a straight line or curved path!
here it is curved path ie part of circle
i really dont no how to xplan da concept here !
hopefully u already no it!
like in magnetic fied
u can say dat electric force acting is equal to centripetal force infact is the source of centripetal force
its bout da angles i guess
hmmmmmmmmm
i nvr thought bout it !
let me confirm it later!
if u no it tell me 2!

 

[danfriday92]

but, it says here the answer is D..........

 

[DragonCub]

The answer to Q 29 IS D.
First, think about what condition makes a circular motion? The force is required to be ALWAYS PERPENDICULAR TO the direction of motion!!!! But is it like this way in the question?? The force on the electron acts towards the upper plate all the time, it goes no longer perpendicular to the electron's motion as soon as electron changes motion status!! It's simply like gravity acting on a projected ball. The path is definitely a PARABOLA!!! Is a parabola a part of a circle? That's totally ridiculous...

 

[workinghard]

get it !
geez ur passionate bout makin a point@
i accidentally skipped da word curved while readin al da options !
thnx anyway!
sorry 4 time wastage: sorry: