Physics: Post your doubts here!

[student2]

View attachment 62076

thnx again. i understood ths

 

[Sharukh khan]

can some one explain this please?

 

[Sharukh khan]

caca some one explain b part ii

 

[sj0007]

can some one explain this please?

They have already provided you with the electric field strength and the charge and are asking you what the additional charge should be to have the electric field strength as 2x10^6
We know that E=kq/(r^2) so we can use the given information to get a value for k/(r^2) since these values will remain constant throughout the question (there is nothing about a change in distance and k is a constant).
So put in the given values and you will find q/(r^2) to be equal to (E/q =) 2.5 x 10^12
Next, use this to find q, plugging in E as 2 x 10^6 (from the same equation E = kq/(r^2)).......... you will get the answer as 8 x 10^-7
Subtract 6 x 10^-7 from this to find the additional charge as 2 x 10^-7

 

[sj0007]

caView attachment 62084ca some one explain b part ii

Use the fact that <c^2> is directly proportional to the kelvin temperature
Cross multiply: 1.9 x 10^6 ------------> (32+273)
? -------------> (80+273)
Once you get the mean square speed at 80 (that is, '?'), square root it to get root mean square speed

 

[Sharukh khan]

Use the fact that <c^2> is directly proportional to the kelvin temperature
Cross multiply: 1.9 x 10^6 ------------> (32+273)
? -------------> (80+273)
Once you get the mean square speed at 80 (that is, '?'), square root it to get root mean square speed

thank youu sooo sooo much bro. thanks a lot . i just got it

 

[student2]

the text bk says tht whn ice is melted energy frm surroundings will conduct into tjhe ice so "L" (latent heat of fusion) is underestimate. bt y can't v say tht energy frm heater is lost 2 surroundings? pls any1?

 

[Sharukh khan]

can any one explain this beacuse according to me centripetal force = gravitational force So why he is asking same question and why are there 2 difffrent asnswers?

 

[Sharukh khan]

also iam confused in last 2 parts bcz accroding to me . reading on newton meter=9.8 into mass but this not the answer

 

[kanwal1]

can someone please explain this
9702/41/M/J/16 Q6 complete

 

[rahimshah98]

Hey guys, how many significant figures shoud our answers in P4 be?
Same as the least number of s.f in the raw data?

 

[Cadence]

3

Hey guys, how many significant figures shoud our answers in P4 be?
Same as the least number of s.f in the raw data?

 

[techgeek]

Someone pleeassse explain these sketches. MS says smooth curves and I'm not getting how!

 

[amina1300]

Can anyone give me some tips for my Alevels physics practical? I have 7 days till my practical and I did only 5-6 practicals in school which were basically not related to the any spring or electricity questions so... I dont have much hands on experience.

 

[Rizwan Javed]

Someone pleeassse explain these sketches. MS says smooth curves and I'm not getting how!
View attachment 62119

For the first one, if you see the equation for electric potential which is V = Q/(4*pi*e*r) you can easily see that V is inversely proportion to 'r'. So when 'r' is double, V is halved. The electric potential remains same (constant) till R. Then after that when R is doubled, V is halved, so the curve must pass through (R, Vs) & (2R, 0.5Vs).

Do the same thing with the next graph.

 

[techgeek]

For the first one, if you see the equation for electric potential which is V = Q/(4*pi*e*r) you can easily see that V is inversely proportion to 'r'. So when 'r' is double, V is halved. The electric potential remains same (constant) till R. Then after that when R is doubled, V is halved, so the curve must pass through (R, Vs) & (2R, 0.5Vs).

Do the same thing with the next graph.

Yeah thanks..
I got that too
btw how did we have to sketch that graph in paper about Hall voltage?

 

[student4563543]

A truck of mass 500kg moves from rest at the top of a section of track 400 m long and 30 m high, The frictional force acting on the truck is 250 N throughout its journey.What is the final speed of the truck? Help please. this is from october november 2016 varient 1 answer should be 14ms-1

 

[Enferno]

A truck of mass 500kg moves from rest at the top of a section of track 400 m long and 30 m high, The frictional force acting on the truck is 250 N throughout its journey.What is the final speed of the truck? Help please. this is from october november 2016 varient 1 answer should be 14ms-1

Total Initial Energy=Energy Wasted + Final Energy
The truck starts from rest so :
Potential Energy=Frictional Energy + Kinetic Energy
m*g*h = F*d + 0.5 * m*v^2
500*10*30=250*400 + 0.5*500*v^2
150,000 - 100,000=250*v^2
v^2= 200
hence
v = 14.1 ms-1

 

[techgeek]

won't it be too fast to measure period of such oscillations?
how do we do it then?

 

[selrey]

won't it be too fast to measure period of such oscillations?
how do we do it then?View attachment 62163

I am not quite sure, but our teacher told us that for such qs measure time and number of oscillations performed during that time and then divide the total time taken by the number of oscillations. And repeat the experiment atleat twice and then take an average of the times taken.