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help with some as physics please

im currently looking through a past AS practicle paper and just a bit confused with one of thw questions.
"Measure the angle 0 that it makes with the bench usig a trigonometic method. Describe how you did this.
by this does it mean using trigonometry or use a protractor to measure the angle? because in the mark scheme all i c is the answer

and a couple of elctricity questions:
"Calculate the mass of copper that is needed to give a wire 0.081mm in diameter a resistance of 200ohms.
the resistivty of copper is 1.7*10^-8
the density of copper is 8900kg m^-3

thanks, who else here have their physics practical exam tomorrow?
Reply 1
hero
im currently looking through a past AS practicle paper and just a bit confused with one of thw questions.
"Measure the angle 0 that it makes with the bench usig a trigonometic method. Describe how you did this.
by this does it mean using trigonometry or use a protractor to measure the angle? because in the mark scheme all i c is the answer




and a couple of elctricity questions:
"Calculate the mass of copper that is needed to give a wire 0.081mm in diameter a resistance of 200ohms.
the resistivty of copper is 1.7*10^-8
the density of copper is 8900kg m^-3



thanks, who else here have their physics practical exam tomorrow?


Using trigonometry, protractors tend to be pretty inaccurate.



Resistance = (resistivity*length)/area

length = (resistance*area)/resistivity

length = (200*5.15E-9)/(1.7E-8)

length = 60.62m

So, volume = length x area

volume = 3.12E-7

mass = volume x density

mass = 3.12e-7 x 8900 = 2.78e-3 kg

This all assumes a perfectly circular cross section - are you sure it's 0.081mm? It is a very very fine wire! 0.81 would be far more likely, in which case, follow the calculations through yourself.