Formula Calculations Help!

[steve100]

Hi

Was wandering if someone could help, I'm a first year level 2 student and we have just started calculations and I'm stuck on a couple:

1. Calculate the thickness of an aluminium busbar 60mm by 12m long which has a resistance of .000946 ohms (given that aluminum has a resistivity of 2.84 x 10-8)?

Do I work out the area in mm2 first then the thinckness? If so how do i then work out the thickness?

2. Calculate the diameter of an aluminium busbar which is 24 m long and whose resistance is .000139 ohms (given that aluminum has a resistivity of 2.84 x 10-8)?

Again do i work out the area first (which i have worked out to be 4903.6mm2, think this is right?) then calculate the diameter? If so how do you calculate the diameter from the area?

Help would be appreciated

Steve

 

[mwm]

Try this.
Area= Resistivity x Length (in meters) / Resistance

then width= Height / Area

I think this is right perhaps someone on here could check this..

 

[telectrix]

1. cross sectional area is a x b where a is thickness, b is width. so a= area/b

2. " " " is pi x r squared, where r is radius and pi is not on my keyboard ( 3.142 ) so r squared. is area/3.142 find square root of r squared and x 2 for dia.

 

[steve100]

1. cross sectional area is a x b where a is thickness, b is width. so a= area/b

2. " " " is pi x r squared, where r is radius and pi is not on my keyboard ( 3.142 ) so r squared. is area/3.142 find square root of r squared and x 2 for dia.

Thanks for this, not sure if i have it right but gave it a go.....

 

[steve100]

Thanks for this, had a go not sure if its right, but at least i tried.....

 

[Sintra]

1. Area = Resistivity X L / R

Area = 0.000000284 x 12 / 0.000946

Area = 0.0036 Sq M

Volume = Length X Width X Thickness

Thickness = Area / Length X Width

Thickness = 0.0036 / 12 X 0.06

Thickness = 0.0036 / 0.72

Thickness = 5 mm

Think thats it.


2. Volume = Resistivity X L / R

Volume = 0.000000284 X 24 / 0.000139

Volume = 0.049 Sq M

pi X r X r = Area X Length

pi X r X r = 24 / 0.49

pi X r X r = 489

Diameter = pi X r X r / pi Sq Rt r X 2

Diameter = 489 / pi = 155.65 Sq Rt = 12.5 X 2

Diameter = 25mm

 

[telectrix]

1. Area = Resistivity X L / R

Area = 0.000000284 x 1.2 / 0.000946

Area = 0.00036 Sq M

Area = Length X Width X Thickness

Thickness = Area / Length X Width

Thickness = 0.00036 / 1.2 X 0.06

Thickness = 0.00036 / 0.072

Thickness = 5 mm

Think thats it.

think not quite right there sintra, VOLUME = L x W X T, area of cross section is Wx T ( i think )

 

[Sintra]

Thought about it that much i've gotten myself confused will look at it again later when the old head clears. But yes i seem to have mixed up area and volume. Changed it about a bit but still not sure.

 

[Gavin121]

The Formula Calculator Products, FC Free, FC Lite, FC Arithmetic, FC Scientific and FC Max, are just calculators. Yes, they do look different, but they are just calculators, and there is an FC Product for every calculator user. They look different because they use a much more beneficial method of calculation entry – they are typed into edit boxes rather than being performed using buttons, although there is an option of combining the use of buttons with typed-in calculations in some of the FC Products. See the Benefits of Formula Calculators for a list of the reasons why this is a much more advantageous method of calculation entry.