Answer:
3200 ft-lb
Step-by-step explanation:
To answer this question, we need to find the force applied by the rope on the bucket at time ![t](https://tex.z-dn.net/?f=t)
At ![t=0, the weight of the bucket is 6+36=42 \mathrm{lb}](https://tex.z-dn.net/?f=t%3D0%2C%20the%20weight%20of%20the%20bucket%20is%206%2B36%3D42%20%5Cmathrm%7Blb%7D)
After
seconds, the weight of the bucket is ![42-0.15 t \mathrm{lb}](https://tex.z-dn.net/?f=42-0.15%20t%20%5Cmathrm%7Blb%7D)
Since the acceleration of the bucket is the force on the bucket by the rope is equal to the weight of the bucket.
If the upward direction is positive, the displacement after
seconds is ![x=1.5 t](https://tex.z-dn.net/?f=x%3D1.5%20t)
Since the well is 80 ft deep, the time to pull out the bucket is ![\frac{80}{2}=40 \mathrm{~s}](https://tex.z-dn.net/?f=%5Cfrac%7B80%7D%7B2%7D%3D40%20%5Cmathrm%7B~s%7D)
We are now ready to calculate the work done by the rope on the bucket.
Since the displacement and the force are in the same direction, we can write
![W=\int_{t=0}^{t=36} F d x](https://tex.z-dn.net/?f=W%3D%5Cint_%7Bt%3D0%7D%5E%7Bt%3D36%7D%20F%20d%20x)
Use
and ![F=42-0.15 t](https://tex.z-dn.net/?f=F%3D42-0.15%20t)
![W=\int_{0}^{36}(42-0.15 t)(1.5 d t)](https://tex.z-dn.net/?f=W%3D%5Cint_%7B0%7D%5E%7B36%7D%2842-0.15%20t%29%281.5%20d%20t%29)
![=\int_{0}^{36} 63-0.225 t d t](https://tex.z-dn.net/?f=%3D%5Cint_%7B0%7D%5E%7B36%7D%2063-0.225%20t%20d%20t)
![=63 \cdot 36-0.2 \cdot 36^{2}-0=3200 \mathrm{ft} \cdot \mathrm{lb}](https://tex.z-dn.net/?f=%3D63%20%5Ccdot%2036-0.2%20%5Ccdot%2036%5E%7B2%7D-0%3D3200%20%5Cmathrm%7Bft%7D%20%5Ccdot%20%5Cmathrm%7Blb%7D)
![=\left[63 t-0.2 t^{2}\right]_{0}^{36}](https://tex.z-dn.net/?f=%3D%5Cleft%5B63%20t-0.2%20t%5E%7B2%7D%5Cright%5D_%7B0%7D%5E%7B36%7D)
![W=3200 \mathrm{ft} \cdot \mathrm{lb}](https://tex.z-dn.net/?f=W%3D3200%20%5Cmathrm%7Bft%7D%20%5Ccdot%20%5Cmathrm%7Blb%7D)
57.296 degrees, so welcome
Answer:
-10
Step-by-step explanation:
since the answer is positive, we need a negative number, if we use -10,two negatives makes a positive, so it becomes
-8 +10=2
13,0,15!!.!:&:&:&;8;&;!,$&: s