- #1
natasha13100
- 58
- 0
Homework Statement
Two engineers are working together in a competition to launch a pumpkin as high as possible using a launching device that must be kept within a certain height. Since the engineers have a height restriction, they want to accelerate the pumpkin to a large speed before releasing it. They decide a good way to get the pumpkin moving fast is to attach the pumpkin to a vertical wheel turned by a motor.
The first engineer suggests that when the wheel is turning as fast as possible at its constant rate w, the pumpkin can be released so that it goes straight upwards.
The other engineer gets out a notebook, runs through some physics calculations, and concludes that releasing the pumpkin straight up will not achieve maximum height. If the wheel spins at a constant angular velocity w, at what angle Θ should the pumpkin be released to reach the highest distance from the ground?
In your calculations, use the small angle aproximations for the sinΘ and cosΘ, and assume the wheel is spinning quickly. Use g, R, and W in your answer. Hint: what are the necessary terms to keep in your small angle approximation?
Diagram is attached.
Homework Equations
v=Rw
a=Rα
v=vi+at
x=xi+vixt+1/2axt2
vx2=vix2+2axt
x=xi+1/2(vx+vix)(t-ti)
The Attempt at a Solution
I am not sure how to solve this without θ being 0 or H being in my equation. I also do not understand the small angle approximation thing.
Here's what I have:
vx=vsinθ=Rwsinθ
vy=vcosθ=Rwcosθ
0=(Rwcosθ)2+2gH
Here I do one of two things
1. (Rwcosθ)2=-2gH
Rwcosθ=√(-2gH)
cosθ=√(-2gH)/(Rw)
θ=cos-1√(-2gH)/(Rw)
2. -(Rwcosθ)2=2gH
H=-(Rwcosθ)2/2g
g is -9.8m/s2 and R and w are constant so H depends on cosθ2.
For H to be maximum, cosθ would be maximum. This happens when cosθ=1.
θ=0