Physics: Post your doubts here!

[Suchal Riaz]

We use P=VI to determine the efficiency? and how do we use it? Can give some examples? Thanks a lot!!

in this question we first found total power, then wasted power and then efficiency.

 

[EddieX]

Aoa,
Guys if anyone of u have COMPLETE PHYSICS DEFINATIONS FOR AS Level ... Please share!
As well as the best and detailed explanation for projectile motion ... Would be well appreciated
URGENT HELP PLEASE!
Thank you

hope this helps mate i found a while back

 

[DeViL gURl B)]

hope this helps mate i found a while back

Thank you soooo MUCH!!
Just wanted to ask .... If u've any other useful notes as well..cuz these seem quite useful thank u
Please share.. If u do

 

[Thought blocker]

Thank you soooo MUCH!!
Just wanted to ask .... If u've any other useful notes as well..cuz these seem quite useful thank u
Please share.. If u do

This might help u more

 

[Princess Raven]

Guys can someone show me how to draw a speed time and velocity time graph for throwing a ball upwards

 

[Thought blocker]

Guys can someone show me how to draw a speed time and velocity time graph for throwing a ball upwards

http://www.examsolutions.net/maths-revision/mechanics/kinematics/velocity-time-graphs/tutorial-1.php

 

[Faithix MFSH]

Can someone please help me with this one?


I know how these questions go but this one seems abit tricky.

They said
A graph is plotted of V/E on the y-axis against 1/R on the x-axis. Express the gradient in terms of F.

Now if the gradient is y/x I get
Gradient = VR/E

Now in terms of F
From the equation, F = VR/E - R
So gradient is F+R

Now R = FE/(V-E)
So if we replace that too in our F+R gradient equation we dont end up with F.

Thats the answer in the ms, F. Gradient = F.

Can someone please solve this and if went right, explain it to me kindly?

Highly appreciate it.

 

[DeViL gURl B)]

This might help u more

Thank u
But isn't this for A2 as in all I need is AS ...

 

[Thought blocker]

Thank u
But isn't this for A2 as in all I need is AS ...

Both are combined, and easy.

 

[DeViL gURl B)]

Both are combined, and easy.

Okha.. Thank u
But actually I was thinkin of being specific .. I mean who wants to read extra stuff
But thank a lot !

 

[GlitteringLights]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w07_qp_4.pdf

hi i have a doubt in this paper, ques # 1 (b)(ii)
this is the answer the ms provides :

"force in cord = weight + centripetal force (can be an equation) ..........................C1
force in cord = (L – 13) × 5/1.8 or force constant = 5.0/1.8 ................................C1
(L – 13) × 5/1.8 = 5.0 + 5/9.8 × L × 10^-2 × 8.7^2
..................................................C1
L = 17.2 cm ...........................................................................................................A1 [4]
(constant centripetal force of 5.0 N gives L = 16.6 cm allow 2/4) "

can someone please clarify whether f=mv^2 /r [centripetal force right?] is being used and why is the 'r' is being multiplied instead of divided? (radius r is Lx10^-2)

 

[Someone2]

Can someone please help me with this one?


I know how these questions go but this one seems abit tricky.

They said
A graph is plotted of V/E on the y-axis against 1/R on the x-axis. Express the gradient in terms of F.

Now if the gradient is y/x I get
Gradient = VR/E

Now in terms of F
From the equation, F = VR/E - R
So gradient is F+R

Now R = FE/(V-E)
So if we replace that too in our F+R gradient equation we dont end up with F.

Thats the answer in the ms, F. Gradient = F.

Can someone please solve this and if went right, explain it to me kindly?

Highly appreciate it.

V=FE/R + E
V=E{F/R + 1}
V/E=F/R + 1 where V/E is y and 1/R is x in the form y=mx+c

hope u get it

 

[EddieX]

Thank you soooo MUCH!!
Just wanted to ask .... If u've any other useful notes as well..cuz these seem quite useful thank u
Please share.. If u do

You are most welcome. Here these are all i have

 

[EddieX]

the rest

 

[Princess Raven]

http://www.examsolutions.net/maths-revision/mechanics/kinematics/velocity-time-graphs/tutorial-1.php

Thank you

 

[DeViL gURl B)]

You are most welcome. Here these are all i have

the rest

Thank youuuu SOOO much!!
Well appreciated ! Thank a lot once again dude!

 

[Talha Irfan]

Guys, is this experiment to determine acceleration of free fall alright?

1) Place a metallic ball attached to an electromagnet in a closed vacuum glass box, with current switched on.
2) Measure the distance from the bottom of the ball to the surface where ball will drop.
3) Switch off the current. Use a digital stopwatch to calculate time the ball takes to travel to surface
4) Use the equation of motion s = 1/2 a t^2 + ut (u=o) => a = 2*distance/(time^2)

To get more accurate result, use longer distance so as to reduce percentage uncertainty both in time and the distance

 

[Snowysangel]

View attachment 41690

Why doesnt the power generated equal to I2R where R=.1+.5+3.4??

 

[Snowysangel]

Can someone please help me with this one?


I know how these questions go but this one seems abit tricky.

They said
A graph is plotted of V/E on the y-axis against 1/R on the x-axis. Express the gradient in terms of F.

Now if the gradient is y/x I get
Gradient = VR/E

Now in terms of F
From the equation, F = VR/E - R
So gradient is F+R

Now R = FE/(V-E)
So if we replace that too in our F+R gradient equation we dont end up with F.

Thats the answer in the ms, F. Gradient = F.

Can someone please solve this and if went right, explain it to me kindly?

Highly appreciate it.

You got the equation in terms of F wrong. F=R(V-E)/E. and shouldn't the gradient be V= E(F/R + 1)--> V/E= F/R + 1 where 1 s the y intercept and F is the graduebt

 

[Snowysangel]

Guys, is this experiment to determine acceleration of free fall alright?

1) Place a metallic ball attached to an electromagnet in a closed vacuum glass box, with current switched on.
2) Measure the distance from the bottom of the ball to the surface where ball will drop.
3) Switch off the current. Use a digital stopwatch to calculate time the ball takes to travel to surface
4) Use the equation of motion s = 1/2 a t^2 + ut (u=o) => a = 2*distance/(time^2)

To get more accurate result, use longer distance so as to reduce percentage uncertainty both in time and the distance

When will we need to describe this?