A person performs a work task at a mechanical efficiency of 20 percent and at total energy output of 15kcal/min. How much energy(kcal/min) is lost as heat? and how much energy(kcal/min) is used to actually perform the work?
Well, well, well, looks like we've got a task that's not pulling its weight! So, this person is operating at a mechanical efficiency of 20 percent, huh? That's not too impressive. It means that only 20 percent of the total energy output is actually being used to do the work, while the remaining 80 percent decides to throw a party and turn into heat!
Now, the total energy output is given as 15 kcal/min. So, to figure out how much energy is lost as heat, we can multiply it by the efficiency percentage. In this case, 80 percent of 15 kcal/min decides to become heat and leaves us with 12 kcal/min lost in the process.
Now, for the energy actually used to perform the work, we can multiply the total energy output by the remaining efficiency percentage. Here, it's 20 percent of 15 kcal/min, which leaves us with a measly 3 kcal/min that is actually doing something useful.
So, to recap: 12 kcal/min are lost as heat and only 3 kcal/min is used for the task at hand. Looks like we've got some energy going down the drain, quite literally!
To calculate the amount of energy lost as heat and the amount of energy used to perform the work, we need to consider the mechanical efficiency.
Mechanical efficiency is defined as the ratio of useful work output to the total energy input. In this case, the mechanical efficiency is given as 20%.
We know the total energy output is 15 kcal/min. Let's denote it as E_total.
To calculate the energy used to perform the work, we can use the formula:
Energy used for work = E_total * Mechanical efficiency
Substituting the given values:
Energy used for work = 15 kcal/min * 0.20
Energy used for work = 3 kcal/min
To calculate the energy lost as heat, we can subtract the energy used for work from the total energy output:
Energy lost as heat = E_total - Energy used for work
Energy lost as heat = 15 kcal/min - 3 kcal/min
Energy lost as heat = 12 kcal/min
Therefore, the energy lost as heat is 12 kcal/min, and the energy used to actually perform the work is 3 kcal/min.
To find out how much energy is lost as heat and how much energy is used to perform the work, we'll need to calculate the energy input and then subtract the energy used for work.
Mechanical efficiency is defined as the ratio of useful work output to the energy input. In this case, the mechanical efficiency is given as 20%. This means that 20% of the energy input is converted into useful work, while the remaining 80% is lost as heat.
First, let's calculate the energy input. The energy input is the total energy output divided by the mechanical efficiency:
Energy input = Total energy output / Mechanical efficiency = 15 kcal/min / 20% = 15 kcal/min / 0.20 = 75 kcal/min
Now, let's calculate the energy used for work. This is simply the energy input multiplied by the mechanical efficiency:
Energy used for work = Energy input * Mechanical efficiency = 75 kcal/min * 20% = 75 kcal/min * 0.20 = 15 kcal/min
Finally, to find out how much energy is lost as heat, we subtract the energy used for work from the energy input:
Energy lost as heat = Energy input - Energy used for work = 75 kcal/min - 15 kcal/min = 60 kcal/min
Therefore, 60 kcal/min is lost as heat and 15 kcal/min is used to actually perform the work.