Physics: Post your doubts here!

[peacce]

dear all,
i need a suggestion and hope that u guys will suggest me the best,
i've got really unexpected result c in maths and d in chem and physics
i'm planning to appear for AS PHY this november and appear for chem accelerated in may/june 2016 as my teacher suggested so, before i appear for chemistry im going to get my papers rechecked because i dont think i can get less than an A.
plz give me your suggestion in this matter... SHOULD I APPEAR FOR PHY IN NOV OR NOT?
P.S. i was expecting STRAIGHT A's

 

[22shimmer22girly]

i will do a2 physics in oct/nov please help

 

[choice]

Calculate the energy needed to lift one kilogram from the surface of venus to a space station in orbit 900km from the surface

 

[princess Anu]

can someone help me in part c?
Ans is 3.67

 

[fmwaz5]

A computer hard disk starts from rest, then speeds up with an angular acceleration of 190 rad/s^2 until it reaches its final angular speed of 7200 rpm.

How many revolutions has the disk made 10.0s after it starts up?

 

[fmwaz5]

View attachment 55814 can someone help me in part c?
Ans is 3.67

T-W = mv^2/r you should get the answer from this equations. since there are two forces acting on to create the centripetal force ; Tension (T) and Weight (W) of the bob. Get it?

 

[fmwaz5]

it's a horizontal plane. i don't think this equation is correct

oh, you're right. I didn't see that. In that case Fc must be equal to Tension, so the formula F= mv^2/r (F= ma) should work.
F= 0.15 x 22.17 (acceleration calculated in b)
= 3.3264 N

 

[princess Anu]

oh, you're right. I didn't see that. In that case Fc must be equal to Tension, so the formula F= mv^2/r (F= ma) should work.
F= 0.15 x 22.17 (acceleration calculated in b)
= 3.3264 N

I got the exact answer via a different method
I equated TSINtheta to Fc ( found in part b)
and Tcostheta to Weight
and found the resultant which was equal to the tension.

Thanks for helping though.

 

[Zash Riyash]

I've been doing noticing in the MCQs lately that certain questions accept power=force x velocity
Whilst, yet other questions accept only power=work done/time taken.

 

[fmwaz5]

I got the exact answer via a different method
I equated TSINtheta to Fc ( found in part b)
and Tcostheta to Weight
and found the resultant which was equal to the tension.

Thanks for helping though.

Great! Had totally forgotten about that method.

 

[bubbles1997]

Aoa everyone. Can somebody please guide me to A2 topical worksheets? I mean question papers? It is difficult to check for a specific chapter in every paper.

 

[shazmina]

http://studentbounty.com/pastpapers...vel/Physics (9702)/2002 Nov/9702_w02_qp_2.pdf
Help please ..... Can some1 please tell me how to draw wave T2 when it lags behind wave T1 Qs 5 B ( i )
Like i have drawn it ... but not so sure whether its right
Thanks in Advance

 

[Tozu Fofo]

Hi
I just started my AS physics course 2 weeks ago and I have a quiz
I don't understand what's the difference between law of conservation of energy and work energy principle

 

[Tozu Fofo]

Please answer me as fast as possible
Thanks

 

[amal sharkawi]

 

[22shimmer22girly]

i need help wid physics past papers solving especially nov 2002...

 

[amal sharkawi]

can anyone help plz ???

 

[amal sharkawi]

can anyone answer this question plzzzz ???

 

[amal sharkawi]

need help plz in this question

 

[princess Anu]

View attachment 56395

need help plz in this question

i) there will be a point in the field between the two, where Moon's gravitational field will cancel out earth's Gravitational field.

See, the resultant gravitational force on a test particle between the two will be equal to Fe (force by EARTH pulling the object towards its centre)- Fm (force by MOON pulling the object towards its centre). At some point, both will be EQUAL AND OPPOSITE. Hence, there would be 0 resultant force on the object!!

ii. Gravitational field will be zero when field by earth = field by moon

GMe/x2 = GMm/ (6ORe - x)^2 ; where Me and Mm are used to show mass of earth and moon respectively.