Physics: Post your doubts here!

[Zaki ali asghar]

reason
View attachment 62525

total resistance of circuit is 3 ohms,suppose the emf of cell is 12V.On lhs the pd would be 2/3*12=8v and on rhs 4v.So I1 would be 8/3=2.67A and I2 would be 4/2=2A so I1>I2

 

[A.Joshua]

Answer is 4%?

Thanks a lot for the answer .... but i really dont know how you get there...

 

[Zaki ali asghar]

What is the order of magnitude of the Young modulus for a metal such as copper?
A: 10^–11 Pa B: 10^–4 Pa C: 10^4 Pa D: 10^11 Pa
9702_w16_qp_11 Q.1
How do we even answer such questions?

Its 10^11

 

[Holmes]

You got me confused by the other answer
For A
Take combined resitance in both loops .
Right loop; Left loop;
1 ohm 2 ohm

V1 + V2 = emf
hence p.d V1 > V2
B and D are incorrect.

Right loop;
Both branches have equal resistances.
Right loop;
more current in 3 ohm resistor than 6 ohm (V=IR)

This gives I1 >I2

thanks

 

[Holmes]

Total Resistance in the Loop where V1 is connected = 2 ohm
Total Resistance in the loop where v2 is connected = 1 ohm
Now, V1 > v2

Total current in the circuit will be divided equally in the second loop where I2 is labelled so I2 is half the current in the circuit. But I1 must be greater than the current in 6 ohm resistor. 2 (I2) = I1 + Current in 6 ohm resistor. Current in 6 ohm resistor must be less than I2.
Hence I1 > I2

THanks

 

[Bishnu Dev]

Thanks a lot for the answer .... but i really dont know how you get there...

I was interested to know whether my answer is right or not before posting the solution.

There's a negative zero error in the device so you need to add the values. (0.8 + 0.2) Uncertainty = (0.02 + 0.02),
Now get the percent uncertainty, (0.04/1) *100

 

[Holmes]

What is the order of magnitude of the Young modulus for a metal such as copper?
A: 10^–11 Pa B: 10^–4 Pa C: 10^4 Pa D: 10^11 Pa
9702_w16_qp_11 Q.1
How do we even answer such questions?

Just remember the YOUNG modulus for any object is 10^11.
learn it.
I found it on Znotes.

 

[A.Joshua]

I was interested to know whether my answer is right or not before posting the solution.

Yeah its right... but why do you add 0.8 and 0.2 rather than subtracting, because the zero error is minus 0.2

 

[Holmes]

-

R is directly proportional to the Length. So 4 times length = 4 times resistance
R is inversely proportional to the diameter square. Diameter is half so resistance is quadrupled. (4 * Resistance)
Combining both = 4 * 4 * R = 192 ohm..... I don't know if it is right

Thanks it make some sense.

 

[Bishnu Dev]

Yeah its right... but why do you add 0.8 and 0.2 rather than subtracting, because the zero error is minus 0.2

In general any zero error is subtracted. In this case (0.8 - (-0.2) ) = 0.8 + 0.2

It's logical. Suppose you're using a micrometer screw gauge and you close it to the end, it doesn't show 0. Instead, it goes beyond 0 which means that it has a negative zero error. For every measurement you take, it will give you a value which is less than the real value and when you add the zero error to the measurement, you will get the real value for it.

 

[Holmes]

anyone

 

[Bishnu Dev]

anyone
View attachment 62528

Speed = distance / time

When distance is X,
For outward flight,
Time = X / 600

For Return Flight,
Time = X/400

Total Time = (X / 600) + (X / 400)
Average Velocity = 2X / Total Time = 480

 

[ughkno]

31 and 32 please

 

[Dynamo]

Anyone please help?

 

[Metallic9896]

View attachment 62530
Anyone please help?

They are asking for a hypothetical relationship, a "possible relationship" as they say. You know that Power depends on v and F, and F depends on v. So power depends on v twice as much as F depends on v. Thus, in a potential relationshiip, the dependence of Power on v must be one exponent higher than the dependence of F on v. A is impossible 'cause this shows the reverse. B and C are impossible cause here both are dependent on v to the same extent. This leaves only D as plausible answer where Power shows dependence on v to the cube while F shows dependence on v to the square. I'm not so good at maths hopefully someone else can explain if I didn't make sense.

 

[Your 69Mom]

Help Please!

 

[amina1300]

View attachment 62531

Help Please!

Take average of the two densities

 

[amina1300]

http://papers.gceguide.com/A Levels/Physics (9702)/9702_s16_qp_13.pdf Q4

 

[Your 69Mom]

Take average of the two densities

Why? and then what?

 

[amina1300]

Why? and then what?

1x10^5 - density * g*h