Work, Energy and Simple Machines

Chapter at a glance

Work done by a force, the work–energy theorem, kinetic and potential energy, power, and how simple machines make work easier. It includes the traditional Himalayan water mill (gharat or panchakki).

What this chapter covers

• 7.1 Work Done by a Constant Force
• 7.2 The Work-Energy Theorem
• 7.3 Forms of Energy
• 7.4 Mechanical Energy
• 7.5 Power
• 7.6 Simple Machines

Key points

• Work is done when a force displaces an object along its direction.
• Work done on a system equals the change in its energy.
• Kinetic energy comes from motion; potential energy is stored by deformation or position.
• Power is the rate of doing work.
• Simple machines change the size or direction of the force needed but do not reduce the total work.

Read the NCERT chapter

Read this chapter in the official NCERT textbook Exploration (2026-27 edition) for free on ncert.nic.in.

Open the NCERT chapter PDF