A 46% efficient device uses chemical energy to generate 570J of electric energy.
1. How much chemical energy is used?
2. A second device uses twice as much energy to generate half as much electric energy. What is its efficiency?
1. Eff. = Eo/Ei = 0.46.
570/Ei = 0.46
Ei=570/0.46 = 1239 J. = Chem energy in.
2. Eff. = 0.5Eo/2Ei = 0.25(Eo/Ei).
Replace Eo/Ei with 0.46:
Eff. = 0.25*(0.46) = 0.115 = 11.5%.
How does Chemical energy perform in terms of energy efficiency and eco-friendliness?
To find the answers to the questions:
1. To calculate the amount of chemical energy used, we use the formula:
Chemical Energy = Electric Energy / Efficiency
Substituting the given values, we have:
Chemical Energy = 570J / 0.46 = 1239.13 J
Therefore, approximately 1239.13 J of chemical energy is used.
2. Let's assume the second device uses x amount of energy to generate half as much electric energy, which is y/2.
Therefore, we have the equation:
Efficiency of the second device = (Electric Energy / Energy Used) * 100
Substituting the given values:
Efficiency of the second device = (y/2) / x * 100
Since the given device is twice as efficient as the second device, we can set up the equation:
46% = 2 * (Electric Energy / Energy Used) * 100
Solving for (Electric Energy / Energy Used):
0.46 * 0.01 = 2 * (Electric Energy / Energy Used)
0.0046 = (Electric Energy / Energy Used)
Therefore, the efficiency of the second device is 0.0046 or 0.46%.
To solve these questions, we need to understand the concept of efficiency. Efficiency is the ratio of useful output energy to the input energy, expressed as a percentage.
1. To find the chemical energy used by the device, we can use the formula for efficiency:
Efficiency = (Output Energy / Input Energy) * 100
Given that the efficiency is 46% and the electric energy output is 570J, we can rearrange the formula to solve for the input energy:
Input Energy = (Output Energy / Efficiency) * 100
Substituting the values, we get:
Input Energy = (570J / 46%) * 100
Now we can calculate it:
Input Energy = (570J / 0.46) * 100 = 1239.13 J
Therefore, the chemical energy used by the device is approximately 1239.13 Joules.
2. For the second device, we are told that it uses twice as much energy (2x) to generate half as much electric energy (0.5x) compared to the first device. Let's calculate its efficiency:
Efficiency = (Output Energy / Input Energy) * 100
Since the second device uses twice (2x) the energy compared to the first device, the input energy will be doubled. Also, the output energy is halved (0.5x). Substituting these values into the efficiency formula:
Efficiency = ((0.5x) / (2x)) * 100
Simplifying it further:
Efficiency = (0.5 / 2) * 100
Efficiency = 25%
Therefore, the efficiency of the second device is 25%.