## Ahsome one year ago Velocity Question

1. ahsome

The world record for fresh hen’s egg throwing is 96.90 m, set in 1981. Assuming no air resistance, what would have been the (a) throwing speed; (b) elevation angle; (c) maximum height; (d) time of flight?

2. ahsome

I'm having some weird issues, where I am given too little information to solve...

3. ahsome

Let $$x$$ be the total velocity $$x_h=x\times\cos\left(\theta\right)$$ $$x_y=x\times\sin\left(\theta\right)$$ $t=\frac{96.90}{x\times\cos\left(\theta\right)}$ $s_y=x_yt+\frac{1}{2}a_yt^2$ $0=x\times\cos\left(\theta\right)\times\left(\frac{96.90}{x\times\cos\left(\theta\right)}\right)+\frac{1}{2}\times-9.8\times\left(\frac{96.90}{x\times\cos\left(\theta\right)}\right)^2$

4. anonymous

If the world record is set then the angle of elevation should be 45 degrees otherwise it would not have been a record

5. ahsome

Then why would they ask for elevation angle..?

6. ahsome

Whoops, thats meant to be $$x\times \sin\left(\theta\right)$$

7. ahsome

For $$x_y$$

8. ahsome

Any dieas @ganeshie8 @UnkleRhaukus ?

9. UnkleRhaukus

i also think it is justified to use 45° as the elevation angle

10. ahsome

But I still don't know why they would ask it in the question... let me look at the solution

11. ahsome

Wow. The angle is 45 degrees in the book -_-

12. ahsome

Can you solve it without knowing the angle?

13. anonymous

its like common sense @Ahsome :P

14. nincompoop

you cannot use common sense in physics

15. ahsome

@nincompoop, TRUTH

16. ahsome

But I guess I'll just assume you had to assume the whole time..?

17. anonymous

any other ideas?? @nincompoop

18. ganeshie8

|dw:1434178782194:dw|

19. nincompoop

|dw:1434178667144:dw|

20. nincompoop

90 degrees would most likely not reach the distance horizontally

21. nincompoop

|dw:1434178899967:dw|

22. ganeshie8

For a given range, the max height could be "anything", so there is no unique answer. To get an unique answer we need to use a bit of common sense here that the given range is the world record (maximum possible for a given velocity)

23. anonymous

thankyou @ganeshie8

24. ahsome

The answer itself says the angle is 45 degrees

25. nincompoop

|dw:1434178985932:dw|

26. nincompoop

45 degree angle is the optimal angle provided the same newton force is applied

27. nincompoop

as the egg elevates gravity is pushing it down

28. ahsome

Then why would part of the question ask what is the angle...

29. nincompoop
30. ganeshie8

They are testing if you know that the maximum is achieved when $$\theta = 45$$ you may prove it if you want to..

31. ganeshie8

*maximum range

32. ganeshie8

You need to assume the starting speed is constant (all humans have more or less same throwing power) and vary only the angle and see which angle produces maximum range

33. nincompoop

correct, and that is determined by the velocity of the egg itself

34. ganeshie8

$R = \dfrac{v_0^2\sin(2\theta)}{g}$ what angle makes $$R$$ large ?

35. ahsome

45 degrees? Since $$45\times 2=90$$ and $$sin(90)=1$$

36. ganeshie8

Yep! maybe just put that for justification

37. nincompoop

correct

38. ahsome

Ahh, thanks @ganeshie8 and @nincompoop and everybody who helped :D

39. ganeshie8

np:) please medal divu.mkr not me

40. ahsome

If you say so @ganeshie8 ;)

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