Test: Energy - ENGAA MCQ

When a body does work, it loses energy. The energy expended in doing work is transformed into other forms, such as heat or sound, demonstrating energy's conversion nature.

Energy is defined in science as the ability to do work. This means that any object that can perform work possesses energy, which can be transformed from one form to another, such as potential energy to kinetic energy.

The law of conservation of energy asserts that energy cannot be created or destroyed; it can only change forms. This means that the total energy in a closed system remains constant, which is fundamental in physics.

When a hammer strikes a nail, it uses kinetic energy, which is the energy of motion. The hammer's movement transfers energy to the nail, driving it into the wood.

Work is calculated using the formula W = F × S, where W is work, F is the force applied, and S is the displacement in the direction of the force. This shows that work depends on both the amount of force and the distance moved.

Kinetic energy is the energy of motion, so a moving car is a prime example. The faster the car moves, the more kinetic energy it possesses, which is dependent on both its speed and mass.

Electric energy is primarily used in electric motors. This energy is converted into mechanical energy to perform work, such as spinning a fan or driving machinery.

Heat energy is not considered a type of mechanical energy. Mechanical energy consists specifically of kinetic and potential energy, which relate to the motion and position of objects, respectively.

Sound energy is the energy produced by vibrating objects. When objects vibrate, they create sound waves that can be heard, demonstrating how energy can be transformed into audible forms.

Potential energy is the energy stored in an object due to its position or shape. For example, a lifted object has gravitational potential energy due to its height above the ground.

The energy released when a fuel is burned is known as chemical energy. This form of energy is stored in the bonds of chemical compounds and is released during chemical reactions, such as combustion.

Energy transformation is significant because it enables various forms of work and processes essential for daily life, including mechanical work, heating, and powering devices, allowing us to perform tasks efficiently.

The energy in a battery is primarily chemical energy, which is converted into electric energy when the battery is connected to a circuit, powering the device.

During a car's braking process, kinetic energy is transformed into heat and sound energy due to friction between the brake pads and the wheels. This demonstrates the conversion of energy from one form to another.

Photosynthesis is the process where plants convert light energy from the sun into chemical energy stored in carbohydrates. This process is essential for life on Earth as it forms the base of the food chain.

In a hydroelectric dam, the potential energy of stored water is converted into kinetic energy when the water is released. This kinetic energy turns turbines, which then generate electricity.

Fossil fuels store chemical energy, which is released when they are burned. This energy is then converted into heat energy for use in power generation and transportation.

The SI unit for measuring work is the joule. One joule is defined as the work done when a force of one newton moves an object one meter in the direction of the force applied.

When a speaker converts electrical impulses into sound, electric energy is transformed into sound energy. This process is essential in audio technology, allowing us to hear music and speech through devices.

Solar energy is considered the ultimate source of energy for Earth. It drives processes like weather, photosynthesis, and the generation of wind and hydro energy, impacting all forms of life.