ICSE Class 8 Physics, Unit 4: Energy

What this unit aims at

Building on previous learning on Energy, the emphasis in this class is on the introduction of gravitational potential energy to children. Look at a swinging bob of a pendulum. When it is at its extreme position (the highest point of its motion), it has gravitational potential energy. When it reaches its mean position (lowest point), it has maximum speed and it has high kinetic energy. In this case, one form of energy changes into other, according to the law of conservation of energy. Energy is the ability to do work. Work is said to be done when a force acting on an object changes the position of the object. For the special case when the object changes its position along the direction of the force, work is given by the product of the force and distance moved by the object. But different persons may take different time to do the same work. Rate of doing work is called power. So energy and

Your child should be able to

• define work
• express work in proper unit
• calculate work done in simple cases
• define kinetic energy
• express kinetic energy in proper units
• solve simple problems based on kinetic energy
• define potential energy
• define gravitational potential energy
• solve simple problems based on gravitational potential energy
• describe energy transformation in daily life situation

Key concepts in this unit

• Concept of Work Unit of Work (Joule)
• Calculation of Work done in simple cases
• Kinetic Energy Basic Concept
• Potential Energy Basic Concept
• Gravitational Potential Energy
• Calculation of kinetic and potential energies from a set of given data (Simple problems and assuming g=10 m/s2)
• Energy transformation in common daily life situations
• Difference between Energy and power