Question
B3.3 Useful Energy and Efficiency pages 215-220 Useful Energy The purpose of a machine is to convert the initial energy input to the type of desired energy output. Energy input refers to the __ Useful energy output refers to the __ . All energy output that is not being used to do useful work is considered __ (e.g. energy lost due to friction). State the input energy.useful output energy, and waste energy in the following situations: 1. Light bulb 2. Truck 3. Human Body __ - Percent efficiency is calculated using the following formula:
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Answer
Energy input refers to the **total energy supplied to a machine**.
Useful energy output refers to the **energy converted by the machine into the desired form**.
All energy output that is not being used to do useful work is considered **waste energy** (e.g., energy lost due to friction).
State the input energy, useful output energy, and waste energy in the following situations:
1. **Light bulb:**
* **Input energy:** Electrical energy
* **Useful output energy:** Light energy
* **Waste energy:** Heat energy
2. **Truck:**
* **Input energy:** Chemical energy (from fuel)
* **Useful output energy:** Kinetic energy (motion)
* **Waste energy:** Heat energy (from engine), Sound energy
3. **Human Body:**
* **Input energy:** Chemical energy (from food)
* **Useful output energy:** Kinetic energy (movement), Thermal energy (body heat)
* **Waste energy:** Heat energy (from metabolic processes)
Percent efficiency is calculated using the following formula:
**Efficiency = (Useful energy output / Total energy input) x 100%**
Useful energy output refers to the **energy converted by the machine into the desired form**.
All energy output that is not being used to do useful work is considered **waste energy** (e.g., energy lost due to friction).
State the input energy, useful output energy, and waste energy in the following situations:
1. **Light bulb:**
* **Input energy:** Electrical energy
* **Useful output energy:** Light energy
* **Waste energy:** Heat energy
2. **Truck:**
* **Input energy:** Chemical energy (from fuel)
* **Useful output energy:** Kinetic energy (motion)
* **Waste energy:** Heat energy (from engine), Sound energy
3. **Human Body:**
* **Input energy:** Chemical energy (from food)
* **Useful output energy:** Kinetic energy (movement), Thermal energy (body heat)
* **Waste energy:** Heat energy (from metabolic processes)
Percent efficiency is calculated using the following formula:
**Efficiency = (Useful energy output / Total energy input) x 100%**
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