A. IMA: 4
The Ideal Mechanical Advantage (IMA) is given by:
![IMA = \frac{d_i}{d_o}](https://tex.z-dn.net/?f=IMA%20%3D%20%5Cfrac%7Bd_i%7D%7Bd_o%7D)
where
is the input distance
is the output distance
For the pulley system in this problem,
and
, so the IMA is
![IMA=\frac{3.90 m}{0.975 m}=4](https://tex.z-dn.net/?f=IMA%3D%5Cfrac%7B3.90%20m%7D%7B0.975%20m%7D%3D4)
B. MA: 3.59
The actual mechanical advantage (AMA), or simply the Mechanical Advantage (MA), is given by
![MA=\frac{F_o}{F_i}](https://tex.z-dn.net/?f=MA%3D%5Cfrac%7BF_o%7D%7BF_i%7D)
where
is the output force and
is the input force. For the pulley system in this problem,
and
, so the MA is
![MA=\frac{1345 N}{375 N}=3.59](https://tex.z-dn.net/?f=MA%3D%5Cfrac%7B1345%20N%7D%7B375%20N%7D%3D3.59)
C. Efficiency: 89.8 %
The efficiency of a machine is equal to the ratio between the MA and the AMA:
![\eta = \frac{MA}{AMA} \cdot 100](https://tex.z-dn.net/?f=%5Ceta%20%3D%20%5Cfrac%7BMA%7D%7BAMA%7D%20%5Ccdot%20100)
Therefore, in this case,
![\eta=\frac{3.59}{4}\cdot 100=0.898=89.8 \%](https://tex.z-dn.net/?f=%5Ceta%3D%5Cfrac%7B3.59%7D%7B4%7D%5Ccdot%20100%3D0.898%3D89.8%20%5C%25)
Yes, think about the difference of swinging a bat and not hitting a ball. It's fairly easy right? Now, when you hit a ball with the bat, you will feel the bat sting your hands. That's the force the ball is exerting on the bat!
32 kg m/s would be the kinetic energy.
I believe there are two correct answers, and those answers are A and D