Prelim Physics Thread (3 Viewers)

InteGrand · Jul 22, 2016

jathu123 said:
please help, an explanation if possible. Thanks
View attachment 33374

$\noindent I think it's meant to be something like `$\text{measured value }\pm\text{ half the limit of reading}$'.$

$\noindent Here, the `measured value' is 13 V, and the limit of reading is 1 V, so half the limit of reading is 0.5 V. So I think it should be $13 \pm 0.5$ V (option (A)).$

jathu123 · Jul 22, 2016

InteGrand said:
$\noindent I think it's meant to be something like `$\text{measured value }\pm\text{ half the limit of reading}$'.$

$\noindent Here, the `measured value' is 13 V, and the limit of reading is 1 V, so half the limit of reading is 0.5 V. So I think it should be $13 \pm 0.5$ V (option (A)).$

Ah okay thankyou!

Fizzy_Cyst · Jul 22, 2016

InteGrand said:
$\noindent I think it's meant to be something like `$\text{measured value }\pm\text{ half the limit of reading}$'.$

$\noindent Here, the `measured value' is 13 V, and the limit of reading is 1 V, so half the limit of reading is 0.5 V. So I think it should be $13 \pm 0.5$ V (option (A)).$

I approve of this post

Green Yoda · Jul 22, 2016

InteGrand said:
$\noindent I think it's meant to be something like `$\text{measured value }\pm\text{ half the limit of reading}$'.$

$\noindent Here, the `measured value' is 13 V, and the limit of reading is 1 V, so half the limit of reading is 0.5 V. So I think it should be $13 \pm 0.5$ V (option (A)).$

Is this in yr 11?

Fizzy_Cyst · Jul 22, 2016

Rathin said:
Is this in yr 11?

Skills based outcome - P12.4a

assess the accuracy of any measurements and calculations and the relative importance of the data and information gathered

Green Yoda · Jul 22, 2016

Fizzy_Cyst said:
Skills based outcome - P12.4a

assess the accuracy of any measurements and calculations and the relative importance of the data and information gathered

Wow I was not aware of this dot point..anyone got notes on this one?

InteGrand · Jul 23, 2016

Rathin said:
Wow I was not aware of this dot point..anyone got notes on this one?

Did your teachers teach you anything related to this when doing pracs?

Green Yoda · Jul 23, 2016

InteGrand said:
Did your teachers teach you anything related to this when doing pracs?

Nope nothing..my teachers are bad :/

eyeseeyou · Aug 3, 2016

Help

A research claims that it has found a new form of nuclear radiation never before observed the laboratory reports that this new form of radiation has the following properties:
1. Can penetrate more than 3 metres f concrete
2. Has moderate ionising power
3. Is deflected by a magnetic field
4. Is deflected by an electric field

Discuss whether this new particle is a form of electromagnetic radiation or particle. Give your reasoning clearly (3 marks)

Green Yoda · Aug 3, 2016

eyeseeyou said:
Help

A research claims that it has found a new form of nuclear radiation never before observed the laboratory reports that this new form of radiation has the following properties:
1. Can penetrate more than 3 metres f concrete
2. Has moderate ionising power
3. Is deflected by a magnetic field
4. Is deflected by an electric field

Discuss whether this new particle is a form of electromagnetic radiation or particle. Give your reasoning clearly (3 marks)

It's a beta particle due to its medium ionising power. This is further proven as it is deflected by both the magnetic and electric fields so it must consist of charge particles (+2 which is equivalent to helium nucleus).

eyeseeyou · Aug 3, 2016

Rathin said:
It's a beta particle due to its medium ionising power. This is further proven as it is deflected by both the magnetic and electric fields so it must consist of charge particles (+2 which is equivalent to helium).

Thanks Rathin

eyeseeyou · Aug 3, 2016

A car of mass 1000kg travelling at 15ms^-1 accelerates to 20ms^-1 in 4 seconds. Calculate the resultant force required to do this.

jathu123 · Aug 3, 2016

a=(v-u)/t
= (20-15)/4=5/4ms^-2

F=ma
=1000*5/4
=1250 N in the direction of it's motion

eyeseeyou · Aug 3, 2016

jathu123 said:
a=(v-u)/t
= (20-15)/4=5/4ms^-2

F=ma
=1000*5/4
=1250 N in the direction of it's motion

Thanks Jathu123

eyeseeyou · Aug 4, 2016

A wire of length 80cm and cross sectional area of 1.2 times 10^-4 m^2 has a resistance of 10 ohms at 25 degrees celcius. Determine the change in resistance if the radius is changed to 5mm

InteGrand · Aug 4, 2016

eyeseeyou said:
A wire of length 80cm and cross sectional area of 1.2 times 10^-4 m^2 has a resistance of 10 ohms at 25 degrees celcius. Determine the change in resistance if the radius is changed to 5mm

Use the fact that the resistance is inversely proportional to the cross-sectional area (along with the formula for the area of a circle, assuming the wire's cross section is circular).

$\noindent (The formula is $R=\frac{\rho L}{A}$, as explained here in the section ``Resistivity and Conductivity'':$

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html .)

Zalkene · Aug 4, 2016

hey, I have a question:

As a result of being hit from behind by a toy truck, a 500g toycar, initially at rest, rolls 12.0m across a floor that applies a constant retarding force of 1.2N to it. The car stops 2.0s after being hit. If the truck was in contact with the car for 0.12s calculate the impulse given to the car.

eyeseeyou · Aug 4, 2016

How has total internal reflection revolutionized modern communication?

Nailgun · Aug 4, 2016

eyeseeyou said:
How has total internal reflection revolutionized modern communication?

fiber optic

eyeseeyou · Aug 4, 2016

Nailgun said:
fiber optic

Do I have to mention core and cladding in this?

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