Question

78\. Identify two forms of energy that are involved in each of the following energy conversions relating to an automobile: (a) lead-acid battery making electricity (b) electricity turning a starter motor (c) starter motor turning a flywheel (d) gasoline exploding into hot gases

Short answer

(a) Chemical to Electrical, (b) Electrical to Mechanical, (c) Mechanical to Mechanical, (d) Chemical to Thermal.

Step-by-step solution

Analyze Lead-Acid Battery Making Electricity

In a lead-acid battery, chemical energy stored in the battery is converted into electrical energy. The chemical reactions within the battery cells generate a flow of electric charge, which can be used to power electrical devices.

Understand Electricity Turning a Starter Motor

In this process, electrical energy is used to power the starter motor. The electrical energy is converted into mechanical energy, as the electricity causes the motor to turn, which begins the process of starting the engine.

Examine Starter Motor Turning a Flywheel

The mechanical energy produced by the starter motor is transferred to the flywheel. This energy transfer results in the flywheel spinning, indicating that mechanical energy is being passed on and utilized to further the system's operation.

Explore Gasoline Exploding into Hot Gases

When gasoline inside an engine combusts, the chemical energy stored in the gasoline is transformed into thermal energy. The explosion of gasoline creates hot gases that expand rapidly, leading to an increase in temperature and pressure inside the engine cylinders.

Key concepts

Chemical Energy

Chemical energy is a type of potential energy stored in the bonds of molecules and compounds. In the context of automobiles, chemical energy plays a crucial role in the functioning of both lead-acid batteries and gasoline engines.

- In lead-acid batteries, chemical reactions between lead plates and sulphuric acid release energy.
- This released energy is transformed into electrical energy, providing power to a vehicle's electrical system.
- When gasoline is used in car engines, its chemical energy is released through combustion.
- This release results in a rapid expansion of gases, converting chemical energy into thermal energy, which introduces motion.

Understanding chemical energy helps make clear how fuel and batteries power the different systems of a vehicle.

Electrical Energy

Electrical energy is a form of kinetic energy resulting from the flow of electric charge. It serves as a crucial intermediary in energy conversions within an automobile's electric systems.

- Originating from chemical reactions in the battery, it powers the starter motor, among other electrical components.
- When you start a car, the battery feeds electrical energy to the starter motor to begin the engine's operation.
- This energy is versatile and can be easily transmitted through circuits.
- Electrical energy provides the necessary spark for combustion, lighting, and other functions within the car.

The efficient conversion and use of electrical energy ensure that a vehicle operates smoothly and effectively.

Mechanical Energy

Mechanical energy is the sum of potential and kinetic energy related to the motion and position of objects. In automobiles, it is crucial for initiating and maintaining movement.

- Generated by electrical energy through the starter motor, it turns the motor's components.
- As this mechanical energy is transferred to the flywheel, it causes it to spin and thus, propelling the rest of the engine into action.
- Vehicles utilize mechanical energy to drive the wheels, ultimately moving the car.
- This type of energy is what you observe as the physical movement of engine parts.

The role of mechanical energy is instrumental in transforming stored energy into the movement, enabling the car to perform as expected.

Thermal Energy

Thermal energy is generated when molecules within a substance are in motion, typically as a result of increased temperature. Within an automobile engine, thermal energy plays a vital role in energy conversion processes.

- It is primarily obtained from the combustion of gasoline.
- As fuel ignites, the chemical energy stored in gasoline turns into thermal energy.
- This heat causes the gases in the cylinders to expand rapidly, exerting pressure.
- The pressure drives pistons, converting thermal energy into mechanical work to move the vehicle.

Efficient management of thermal energy is vital for controlling engine temperature and optimizing performance.