## anonymous 3 years ago The prop. blade of an airplane is 2.80ft, and rotates @ 2200 r/min. What is the linear velocity of a point on the tip of the blade?

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1. anonymous
2. zpupster

Use $v=\omega(r)=\theta/t(r)$ $\theta = 2\pi rad$ t= 1 rev r = .5(2.8)

3. anonymous

so them telling me the length of the blade holds no grounds?

4. wolf1728

Will have to look up how to calculate linear velocity.

5. anonymous

all I could find was angular velocity , and after about 2 hours on a simple problem hat

6. anonymous

isnt linear velocity the speed of the circumference?

7. anonymous

speed over time

8. anonymous

I know there's a relationship between the two.

9. wolf1728

I found this: The formula for finding linear velocity is v = x / t. The x variable is distance traveled, and t is the time it took to travel the distance x. The v variable is the linear velocity. radius = 1.4 feet If prop rotates at 2,200 rev/min that equals 36.666 rev for every second Each turn of the prop means that the tip has traveled 1.4 *2*PI = 8.7964594301 feet Multiplying this by 36.666 rev per second equals 322.54 feet per second.

10. wolf1728

The distance from the prop center to the tip is half of 2.8 or 1.4 for each turn of the prop the tip must travel 1.4*2*PI feet.

11. anonymous

so we take 2.80 and multiply in 1/2, that gives us half the blade length which is 1.4 ft. is that 1.4x2xpie?

12. wolf1728

which equals 8.7964594301 feet

13. anonymous

now is that ft per second?

14. wolf1728

eventually it is feet per second. At this point we are only determining the distance traveled - which is 8.796 feet

15. anonymous

persistence pays off i found my page

16. anonymous

I'd like to thank ehuman and wolf1728, I couldn't have done it without you!

17. anonymous

wait what am I talking about, im not done here.

18. zpupster

(2200revs/min)(2 pi rad/rev)(1.4ft)=? that is the equation you need

19. zpupster

compare it to what i gave you before