Learn Class 5 Science - Force and Energy

Force

Pushing or pulling on an object is referred to as force. An external force directs something to move or changes the direction in which it moves. Objects that are moving can be stopped by force.

Types of forces

• Muscular force - It is obtained when arm or leg muscles exert force. Ex: pulling a door, pulling a bed, riding a bicycle.
• Gravitational force - A gravitational force attracts objects of mass with mass. It depends on the shape and size of the objects.
• Frictional force - When two surfaces are in contact, friction is always exerted in the opposite direction of movement.
• Elastic friction - Whenever an object attempts to return to its original state, an elastic force will act in the direction in which it goes.
• Mechanical force - In mechanical force, something that causes a change in state in a system of objects is directly in contact with another and results in some form of mechanical force.

Energy

Energy is the capacity to perform work.

The form of energy varies.

• Light energy - By emitting light energy, the sun allows us to see what's around us. E.g., Bulb.
• Heat energy - The combustion of fuels like gasoline, diesel, and wood provides heat. E.g., Cooking requires heat energy.
• Sound energy - A vibration occurs when force is applied to an object. E.g., A drum's strike produces sound.
• Electrical energy - This type of energy powers electrical appliances.
• Mechanical energy - Mechanical energy is the amount of energy an object possesses because of movement or stored positional energy. Kinetic energy or potential energy may be involved.
• Wind energy - A windmill works by turning blades and generating electricity. The system is smoke-free and eco-friendly.
• Water energy - This energy is generated when water flows through turbines.
• Solar energy - Solar power is the energy we obtain from the sun, which is then converted into electrical energy for the use of machines.
• Geothermal energy - Energy derived from the earth's core is geothermal energy.