# Power dissipation

1. Oct 22, 2008

### soupastupid

1. The problem statement, all variables and given/known data

2. Relevant equations

P=F*V

3. The attempt at a solution

why isn't it

P = Cd(A^2)(v^2) * (v)

i dont see what i could do

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2. Oct 23, 2008

### Staff: Mentor

This is correct.

But this is not. You made an error when you substituted for F in the power equation. Redo it, paying attention to each factor in the drag formula.

3. Oct 23, 2008

### soupastupid

ok i figured out the first part

how do i figure out part B?

I kno the power is proportional to v^3
and so if i increase the power by 10%
i should get

??

if Pi = -(vi^3)AC_d

then 1.1Pi=-(vf^3)AC_d

Pi = (-(vf^3)AC_d ) / 1.1

(vf^3) = 1.1(vi^3)

then what?

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4. Oct 23, 2008

### Staff: Mentor

Solve for Vf in terms of Vi. (Take the cube root of both sides.)