Question

you can make a smoothie in a blender with a power of 300 watts and an efficiency of 80 percent. how much energy is actually being used to make the smoothie in 180 seconds?

a. 43,200 j
b. 52,060 j
c. 10,800 j
d. 45,875 j

Explanation:

Step1: Calculate total input energy

The formula for energy is $E = P\times t$, where $P = 300$ W and $t=180$ s. So $E_{input}=300\times180 = 54000$ J.

Step2: Calculate actual (useful) energy

The efficiency $\eta = 80\%=0.8$. The formula for efficiency is $\eta=\frac{E_{output}}{E_{input}}$. So $E_{output}=\eta\times E_{input}=0.8\times54000 = 43200$ J.

Answer:

A. 43,200 J