1. ## SAT Maths

How would answer this question? Do you need to set up equations with variables?

2. ## Re: SAT Maths

You can set up two equations for the two different conditions:

$\displaystyle q_1 = \frac 1 2 n v_1^2$

$\displaystyle q_2 = \frac 1 2 n v_2^2 \ = \ \frac 1 2 n (1.5 v_1)^2$

Then determine the ratio of q2 to q1.

3. ## Re: SAT Maths

Let q1 be the dynamic pressure of the slower fluid moving with velocity v1, and let q2 be the dynamic pressure of the faster fluid moving with velocity v2. Then

v^2=1.5v1

Given the equation q=1/2nv^2, substituting the dynamic pressure and velocity of the faster fluid gives q2=1/2n(v2)^2. Since v2=1.5v1, the expression 1.5v1 can be substituted for v2 in this equation, giving q2=1/2n(1.5v1)^2. By squaring 1.5, you can rewrite the previous equation as

q2=(2.25)(1/2)n(v1)^2=(2.25)q1

Therefore, the ratio of the dynamic pressure of the faster fluid is

q2/q1=2.25q1/q1=2.25

Would this be the solution?

4. ## Re: SAT Maths

Originally Posted by JLin7
Therefore, the ratio of the dynamic pressure of the faster fluid is

q2/q1=2.25q1/q1=2.25

Would this be the solution?
Yes indeed! Although you have a typo in your first equation - that should be v2=1.5v1 instead of v^2=1.5v1.