# Having trouble getting a formula to work

Copper Contributor

# Having trouble getting a formula to work

Hello everyone,

I am following a course about engineering coolinginstallations and we have a formula we use to calculate the amount of energy we lose thru an open door.

however i'm having difficulty getting this formula to work in excel.

can anybody help me with this?

the formula is: kf*t*P*A*sqrtH*(1-Pu/Pi)1/2*deltah=Q

everything works except the 1/2 part.

example: 0.612*15*1.25*(2*2.5)*sqrt2.5*(1-(1.2/1.25))1/2*72.5=1315.41KJ

4 Replies

# Re: Having trouble getting a formula to work

@Gijs90 Try this:

=0.612*15*1.25*(2*2.5)*SQRT(2.5)*(1-(1.2/1.25))/2*72.5

Though this returns 131.5409, not 1315.41.

# Re: Having trouble getting a formula to work

@Gijs90  wrote:

``0.612*15*1.25*(2*2.5)*sqrt2.5*(1-(1.2/1.25))1/2*72.5=1315.41KJ``

=0.612*15*1.25*(2*2.5)*SQRT(2.5)*(1 - 1.2/1.25)^(1/2)*72.5

results in 1315.40868545317, which rounds to 1315.41.

But note that x^(1/2) is just another way to write SQRT(x).  So another way to write the formula is:

=0.612*15*1.25*(2*2.5)*SQRT(2.5)*SQRT(1 - 1.2/1.25)*72.5

But that could be just GIGO.

Please attach a jpg of the math formula as it appears in your course source so that we can vet your Excel interpretation, in the first place.

And please provide a link to a webpage that has the same math formula with an explanation of it terms.

I tried find it with a google search for "calculate the amount of energy we lose thru an open door" without quotes, to no avail.

# Re: Having trouble getting a formula to work

Excel will allow the use of defined names to provide more coherent representations of formulas.

``= kf * t * P * A * SQRT(H) * (1-Pu/Pi)^0.5 * Δh``

# Re: Having trouble getting a formula to work

Hello @Gijs90

You can check out the below help document provided by Microsoft:

Best Regards,