Explanation for Question 35 From the Math (Calc) Section on the Official Sat Practice Test 4
So here are number 35 or given an equation for Q and Q is 2 the dynamic pressure generated by fluid moving at velocity V. 3 So V is speed velocity and N is a constant density 4 of the fluid, right? So, and is the density and because it's constant, 5 that means that the density is always going to be the same number. 6 And then we're told that engineer uses the formula to find the dynamic 7 pressure of a fluid V and the same pressure or the pressure 8 of the same fluid moving at a higher speed, 9 1.5 times the velocity. And so we need to find the ratio of the 10 dynamic pressure of the faster fluid to the ratio of the slower fluid. 11 So we're going to write two equations here, right? 12 We're going to write a slow and we're going to write a fast and 13 for the slow, I'm going to keep a lowercase Q, 14 but for the fast, I'm going to write upper case queue. 15 So that shows me that the slow queue is little and the big queue 16 is fast. So now I have different variables to help me out. 17 Right. And the slow queue is only moving it V whereas fast queue, 18 right? It's moving it 1.5 V. 19 And so that squared is important. That squared is actually going to go on 20 the 1.52. So if I were to simplify that 1.5 squared is 2.25. 21 So 2.2, five times V squared, 22 right? And so now that we've seen that we need to know the ratio 23 of, um, faster to slower. 24 And so if it wants the ratio of fast to slow, 25 remember we can write ratios of fractions where the colon becomes a fraction ba...