but how?
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Physics, Chemistry and Biology: Post your doubts here!
- Thread starter semsemhosam
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It's the speed of sound (in air)
It's fixed. It's given in our textbooks, too.
Like speed of sound is 3.0 X 10^8, speed of sound is 330 M/s
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can anyone solve q.5 of http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w11_qp_32.pdf
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Alright, here goes nothing!
3bii)
The arm is in equilibrium thus not only are moments equal but upward forces are equal to downward forces. The total downward forces are 140N (20N+120N) and the total upward forces are 2130N - therefore for the forces to be equal there must be a downward force to balance it out so they're both 2130 N - so 2130-140=1990N
So downward force of 1990N
1c)i)
This one is relatively easy ; basically it's speed=distance/time. Distance is 23/100 = 0.23m and time is 22/1000=0.022ms.
So 0.23/0.022 =1.13
3)
I remember this question. It's a long, irritating story.
Okay for a) Lets say the pressure at the top is 'x' and the pressure at the bottom is 'y' so basically this question asks for y-x
the pressure at the top is pgh (density/gravitational acceleration constant/height) and the pressure at the bottom is pg(h+0.07)
In this case, h is the distance from the top of the block to the top of the water level. The distance from the bottom will be h + the height of the block i.e. 0.07
so y-x = pg(h+0.07)-pgh (obviously p and g are the same, because its same liquid on same planet)
so using some basic maths, take pg as common factor and y-x=pg(h+0.07-h)=pg(0.07)
so the difference in pressure is basically just the density x 10 x 0.07 - 1000x10x0.07=700Pa
Sorry if it doesn't make sense, it's hard to explain :|
b) Upward force is equal to downward force, since it's not moving
For downward force, pressure = force/area
area is 0.21*0.1 = 0.021m^2
We know that pressure is 700
So force = area * pressure = 0.021*700 =14.7N
c)When it's released the only downward force is the mass (or weight caused by it) so 3.09*10 = 30.9N
The net force is the downward force - upward force = 30.9-14.7=16.2N
Force = mass * acceleration
acceleration = force/mass = 16.2/3.09=5.24m/s^2
6c) I'll make a diagram for you soon if I can but sorta hard to explain
3b)Look at picture attached
5b)ii)Alright, b(i) shows that useful power is 312J
Efficiency = Useful Power output/Total power input
we want total power input
total power input = useful power output/efficiency
= 312/12% (NOTE PERCENT! 12% =0.12!)
= 2600W
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can someone please explain this sentence to me
"Show understanding that the direction of an induced e.m.f. opposes the change causing it"
Its mentioned in the syllabus.
"Show understanding that the direction of an induced e.m.f. opposes the change causing it"
Its mentioned in the syllabus.
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I deserve a cookie for that...Alright, here goes nothing!
3bii)
The arm is in equilibrium thus not only are moments equal but upward forces are equal to downward forces. The total downward forces are 140N (20N+120N) and the total upward forces are 2130N - therefore for the forces to be equal there must be a downward force to balance it out so they're both 2130 N - so 2130-140=1990N
So downward force of 1990N
1c)i)
This one is relatively easy ; basically it's speed=distance/time. Distance is 23/100 = 0.23m and time is 22/1000=0.022ms.
So 0.23/0.022 =1.13
3)
I remember this question. It's a long, irritating story.
Okay for a) Lets say the pressure at the top is 'x' and the pressure at the bottom is 'y' so basically this question asks for y-x
the pressure at the top is pgh (density/gravitational acceleration constant/height) and the pressure at the bottom is pg(h+0.07)
In this case, h is the distance from the top of the block to the top of the water level. The distance from the bottom will be h + the height of the block i.e. 0.07
so y-x = pg(h+0.07)-pgh (obviously p and g are the same, because its same liquid on same planet)
so usi...........
Thank youuu som muchthanks that helped me 2
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That's Lenz's Law
Example:
If a magnet is pushed into a coil, north face first , it will induce a current in the coil. This current will move in a direction in such a way to oppose the thing that caused it; that is, the insertion of the magnet.
In other words it will create a current so that the north is at the top where the magnet is being pushed in. This means the two Norths will be facing each other and the magnet will (at least attempted) pushed out.
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You deserve more than one cookie ^^, thank you. (sorry for the late reply)
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please help
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s10_qp_32.pdf
question 10 b! i have studied y plates can deflect the beam in vertical and x plates in horizontal but in marking scheme its oppositre they wanna reduce the peak to peak distance and its horizontal so they should make change in time base ryt?
please help
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s10_qp_32.pdf
question 10 b! i have studied y plates can deflect the beam in vertical and x plates in horizontal but in marking scheme its oppositre they wanna reduce the peak to peak distance and its horizontal so they should make change in time base ryt?
please help
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I AM A BIT CONFUSED !!! I NEED SOME ONE TO SHOW ME WHAT TO DO IN Q 6 B OF THE PAPER IN THE LINK ATTACHED http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_31.pdf ........
MARKSCHEME SAYS :
(b)
reflection at Q only, no further reflections B2
(allow B1 only, if there is one further reflection at lower surface)
(give B0 for more than one further reflection)
MARKSCHEME SAYS :
(b)
reflection at Q only, no further reflections B2
(allow B1 only, if there is one further reflection at lower surface)
(give B0 for more than one further reflection)
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http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s07_qp_3.pdf
Plz help me
Question 6 b i ,ii and iii
Plz help me
Question 6 b i ,ii and iii
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Well its a bit hard to tell like this, but if only one reflection is allowed then you would have to measure the angle of incidence of the ray with a protractor, and draw an equal angle of reflection. I'm guessing that the reflected ray would just leave the glass fibre, instead of hitting the surface.
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The ray should strike Q and then move to the other end of the optical fibre. There should not be any more reflections.
And:
You will get 1 mark only if you made one more reflection and the lower surface. But you get 0 marks if there is more than 2 reflections.
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http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s07_qp_3.pdf
Please help question 6) B i , ii and iii
Please help question 6) B i , ii and iii
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For 6)b)i) you can clearly tell from the diagram it's 90 degrees.
For b)ii) They mention in the question "at an angle of 43 degrees the ray is partially reflected", meaning the critical angle has to be something a little more then that or it could be 43.
For b)iii) Now that you have the angle of incidence and refraction just use the formula!
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A thermistor is easy, it's basically a resistor that's resistance changes depending on the temperature. If the temperature is HIGH then it's resistance FALLS, and if temperature is LOW then it's resistance INCREASES.
A transistor.. well, it's a device that uses a smaller current to control/switch on a much larger current.
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Since the critical angle is not given in the question, and it states that leaving through point Q, then it means that you have to measure the angle of incident, and reflect it with the same angle, by the use of a medium line. Do this at point Q and at point R, and then draw the middle reflections and medium lines which connect the beam together. That's it.
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Actually, you said the thermistor correct , but the second point you talked about is the relay switch, not a transisitor !!
A transisitor, is a semiconductor device that works as a switch and has three parts, base, collecter and emitter.
Usually it's used in LDR (Light Dependent Resistor) <-- When lisht intensity increase, resistance falls and vise versa