## justinee 3 years ago i neeed need in my hmwk! :/

1. justinee

with*

2. henkjan

What's wrong?

3. Tomas.A

u didn't post question

4. justinee

|dw:1324427060151:dw|

5. Tomas.A

whats R? whats W?

6. justinee

thats what i dont know.

7. justinee

there is also an equation here..

8. Tomas.A

type in whole problem question

9. justinee

Using $a = \left(\begin{matrix}Fnet \\ m\end{matrix}\right) = \left(\begin{matrix}W - R \\ m\end{matrix}\right)$ find Bronco's acceleration at each position. You need to know that his mass is 100 kg, so his weight is a constant 1000 N. Air resistance (R) varies with seed and cross - sectional area as shown.

10. Tomas.A

what is Bronco?

11. henkjan

a dude

12. henkjan

Do you know any air resistance coefficient... Normally it's given as: Fdrag = A*C Where A is area of the person perpendicular to it's direction and C is some sort of air drag constant. Further on, do you know the area (A in previous formula) of mr Bronco?

13. justinee

so what do i need to multiply or divide? or subtract or +

14. henkjan

I don't see how "Air resistance (R) varies with seed and cross - sectional area as shown. " Because it isn't shown

15. justinee

it's just a picture of a guy falling trying to skydive. with an arrow pointing down.

16. justinee

i can take a picture and somehow attach it here..

17. henkjan

If R=0, as you show in your figure, and straight down (as in figure) ... the only acceleration he gets is gravitational acceleration (g=9.81 m/s^2)

18. justinee

so do u know how to calculate it now?

19. henkjan

If there is no air resistance (R=0) and he will just jump straight down, his accelerations are: a(y) = 0 a(x) = 0 a(z) = g = 9.81 m/s (if z points down is positive, note SI units)

20. justinee

what is (y) (x) (z)

21. Tomas.A

axis of coordinates

22. henkjan

coordinate system.. x and y are the horizontal components, z is vertical

23. justinee

ok, so the acceleration is 0?

24. henkjan

in horizontal direction, yes... it's 9.81 m/s2 in vertical direction (down)

25. justinee

oh okay! thanks! :)

26. justinee

i hatteeeeeee physics.

27. henkjan

haha. no worries