Biology; Chemistry; Physics: Post your doubts here!

[Mahnoorfatima]

Internet par mila bhai

7 is C since if we move weight closer,there will be less distance from pivot and less torque so other end will move down to less torque on one end.
29 is B cuz we close s1 n s2 to get a combined resistance of 1.5 and open s3 to make current flow through 4.5 ohm resister that will give a total resistance of 6.

But for the current to flow through 4.5 ohm resistor the switch s3 has to be closed , no? How can the current flow if the switch is open?

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w13_qp_12.pdf
Question 7 and 29 anyone?

7) See if we move W towards the pivot, its moment will decrease as we are decreasing the perpendicular distance
Thus Y will need a lower force to equal the moment of W (to be in equilibirum), It will have less weight, thus less extension. X is the upward force and it will be opposite to W, and it will increase

29) Wait I will upload the picture I took for this

 

[asadalam]

But for the current to flow through 4.5 ohm resistor the switch s3 has to be closed , no? How can the current flow if the switch is open?

If it is closed the current will bypass the resistor.Thus we have to make current pass through it.Carefully see the diagram.

 

[Awesome12]

Here it is

 

[asadalam]

Here it is

View attachment 42845

aap ki drawing ko salute

 

[asadalam]

Between 3 and 16 minutes, the temperature of the wax is above room temperature
and energy is lost to the room.
Explain, in terms of molecules, why the temperature of the wax remains constant.

So the wax is solidifying in this question.How to answer?

 

[kirann]

 

[FLRNAB]

Between 3 and 16 minutes, the temperature of the wax is above room temperature
and energy is lost to the room.
Explain, in terms of molecules, why the temperature of the wax remains constant.

So the wax is solidifying in this question.How to answer?

KE of molecules is constant. Latent heat is being lost which does not affect temp.

 

[asadalam]

View attachment 42846

A cuz others cant penetrate the skull

 

[asadalam]

KE of molecules is constant. Latent heat is being lost which does not affect temp.

Could you give a more detailed ans?If energy is being given out,why is KE constant? Awesome12

 

[princess Anu]

1.Draw a parallelogram to find the resultant.Ans is B it think.
2.Ans is A?Cuz if you reverse connections with diode going to the positive,it'll rectify the current if attached with negative and wont allow current to flow
3.Ans is A?
4.Ans is C?

how should the diode be connected? like the cathode of diode should be connected in the direction of current?

 

[princess Anu]

In DC there are SPLIT rings that reverse the current every half cycle leading to a continuous rotation

why do they reverse the current ? :s

 

[funky brat]

Between 3 and 16 minutes, the temperature of the wax is above room temperature
and energy is lost to the room.
Explain, in terms of molecules, why the temperature of the wax remains constant.

So the wax is solidifying in this question.How to answer?

Temperature of the wax remains constant although the heat is lost to the surroundings, but as the wax is changing state so the molecules come closer and their kinetic energy is reduced. This kinetic energy accounts for the heat lost from the wax.

 

[funky brat]

In DC there are SPLIT rings that reverse the current every half cycle leading to a continuous rotation

why do they reverse the current ? :s

So that the motor can complete one cycle and keep on turning in the same direction otherwise it would just complete half cycle.

 

[FLRNAB]

Could you give a more detailed ans?If energy is being given out,why is KE constant? Awesome12

Temperature of the wax remains constant although the heat is lost to the surroundings, but as the wax is changing state so the molecules come closer and their kinetic energy is reduced. This kinetic energy accounts for the heat lost from the wax.

KE is constant as temperature is constant.

See this
Q8 C (I)

 

[funky brat]

View attachment 42846

gamma is used in cancer treatment.

 

[peacce]

Ans is C since angle I is equal to angle r, clearly seen.
In B the values are equal but the 2 sets would have the same value. This can't be unless the two incidentrays were parallel to each other so Ans has to be c

nahi aya samajh :'( Can us show the angles by drawing them thru paint

 

[peacce]

Mujhey koi CRO samjha deeeeeeee funky brat Dream.Eater Dark Destination

 

[asadalam]

KE is constant as temperature is constant.

See this
Q8 C (I)

So in solidifying Potential energy is lost?!

 

[FLRNAB]

nahi aya samajh :'( Can us show the angles by drawing them thru paint

Image is not formed at one point in other options.