Physics: Post your doubts here!

[Shah34]

Any tips on phy mcqs like questions posted above there sooooooo hard? How do you tackle these type of qs???

 

[Xylferion]

View attachment 60085

That's a comparator circuit, which basically means that you get an output after comparing the two inputs.

If V+ > V-, you get +5V as your output.
If V- > V+, you get -5V as your output.

They tell you that non-inverting input is at a fixed 1.0V.
That means, for values >1.0V, the output is -5V and for values <1.0V the output is +5V.

You can already see on the graph that it starts of at 2V and continues till it crosses 1V. For this entire duration, V- > V+, so the output = -5V.
Next, you can see that it goes from 1V to 0V and then back to 1V. For this duration, V+ > V-, so the output = +5v.

Hope any of that made sense, if not just reply to this and I'll try to explain it better.

 

[The Sarcastic Retard]

9702_s10_qp_43
Q1b(iii)
Q8(b)

 

[pundadesh]

9702/22/M/J/11 Q2(b)(ii)

A second raindrop has a radius that is smaller than that given in (a). On Fig 2.1, sketch the variation of speed with time for this second raindrop

The sketch is below the original curve

Is it because the radius is smaller therefore the mass is smaller as well (since p=mv) so it reaches terminal velocity earlier?

 

[ashcull14]

That's a comparator circuit, which basically means that you get an output after comparing the two inputs.

If V+ > V-, you get +5V as your output.
If V- > V+, you get -5V as your output.

They tell you that non-inverting input is at a fixed 1.0V.
That means, for values >1.0V, the output is -5V and for values <1.0V the output is +5V.

You can already see on the graph that it starts of at 2V and continues till it crosses 1V. For this entire duration, V- > V+, so the output = -5V.well expl
Next, you can see that it goes from 1V to 0V and then back to 1V. For this duration, V+ > V-, so the output = +5v.

Hope any of that made sense, if not just reply to this and I'll try to explain it better.

well explained thanks a lot

 

[Aishayasin]

PART Bi

 

[funky brat]

View attachment 60128

PART Bi

Since the period is 20ms, it must travel 1/4th of the wavelength in 5ms. Also it should be at it's maximum amplitude so the point should be 1.2/4= 0.3 on the x-axis and 5mm on the y-axis.

 

[funky brat]

9702/22/M/J/11 Q2(b)(ii)

A second raindrop has a radius that is smaller than that given in (a). On Fig 2.1, sketch the variation of speed with time for this second raindrop

The sketch is below the original curve

Is it because the radius is smaller therefore the mass is smaller as well (since p=mv) so it reaches terminal velocity earlier?

Terminal velocity occurs when the weight of an object is equal to the air resistance acting on it. An object with smaller mass has lesser weight and hence less air resistance will be required to achieve terminal velocity. Your explanation is correct.

 

[funky brat]

9702_s10_qp_43
Q1b(iii)
Q8(b)

The two changes that will occur will be the change in speed of the meteorite since the combined gravitational field of both will cause the meteorite to accelerate and also the meteorite will deviate from the path it would have followed otherwise in the absence of the second field.
The decay might occur while you are taking measurements since the half life is so small therefore it isn't suitable.

 

[Aishayasin]

can

Since the period is 20ms, it must travel 1/4th of the wavelength in 5ms. Also it should be at it's maximum amplitude so the point should be 1.2/4= 0.3 on the x-axis and 5mm on the y-axis.

can u draw and show it

 

[funky brat]

can

can u draw and show it

Im not sure if it would be drawn like this. What does the MS say?

 

[funky brat]

I dont have the MS for these so can someone verify the circled part and solve for part b in the other photo?

 

[funky brat]

Part c anyone?

 

[Xylferion]

Part c anyone?

Gain = V out / V in -----------> V out = V in x Gain -------> V out = 95x10^-3 * 71 = 6.75 V

If you chose +/- 5V as your power supply, 6.75 is over that limit. This results in saturation, which when you plot a graph of Voltage/Time, will clip the values beyond 5V.

You don't want this, so you pick the power supply that wont clip the values, which in this case is the +/- 9V supply.

 

[Aishayasin]

Can anyone tell me steps

 

[areeba240]

i have qtn...is giving AS better or giving the complete A LEVEL is better....
EVERYONE PLEASE POST UR OPINION
thanks in advance

 

[Saad the Paki]

View attachment 60136
Can anyone tell me steps

And then you can find the combined resistance : (1/24+1/12)^-1 = 8 ohm
They have equal resistivities as they are made of the same material. So I just equated their resistivities.

 

[Saad the Paki]

i have qtn...is giving AS better or giving the complete A LEVEL is better....
EVERYONE PLEASE POST UR OPINION
thanks in advance

Definitely giving AS is better. Even though I don't have the experience but I'm pretty studying for both the courses at the same time is going to be very tough.

 

[The Sarcastic Retard]

i have qtn...is giving AS better or giving the complete A LEVEL is better....
EVERYONE PLEASE POST UR OPINION
thanks in advance

It depends from person to person. I had a friend who gave 6 subjects in 6 months and scored 6A*s and a friend who is giving just As level since 2 years and yet he is stuck at D. So now as I said, it depends. If you love studying and your complete focus is in studies and wanna score good u need to practice heck so muchhhhhhhhhhhhhhhhhhhhh!!

For me, I think giving As first then A2 is better option as I cant take both load together.
You can give 2 subjects As and A level in november and other 2 in summer and other 2 in next november.. So in just one year you are done with your A levels with 6 subjects, which is so good if u score more than B in it. This is what I think.

Good luck..

 

[The Sarcastic Retard]