Work, Energy, and Simple Machines Mind Map

Work is done by a force when the force causes displacement of an object in the direction of the force or with a component along the displacement.

Always check two things before calculating work: force must act, and displacement must occur along the force or its component.

The sign of work depends on the angle between force and displacement: work is positive when both are in the same direction, negative when opposite, and zero when perpendicular or when displacement is absent.

Draw force and displacement arrows. Same direction gives positive work, opposite direction gives negative work, and perpendicular gives zero work.

The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy.

Look for the word net. The theorem is about total effective work after considering all forces, not only the applied force.

Energy appears in different forms such as mechanical, heat, light, sound, electrical, chemical, and nuclear energy, and it can change from one form to another.

For conversion questions, write the starting form of energy and the final useful form clearly.

Kinetic energy is the energy possessed by a body due to its motion.

In numerical questions, square the velocity first and then multiply by 1/2 m.

Potential energy is the energy possessed by a body due to its position or configuration. In this chapter, gravitational potential energy is mainly used.

Read the reference level carefully. Height in mgh means vertical height from the chosen level, not distance travelled along a path.

Conservation of mechanical energy means that the sum of kinetic energy and potential energy remains constant when only conservative forces like gravity act and friction is neglected.

Mention the condition clearly: mechanical energy is conserved only when friction and air resistance are ignored.

Power is the rate of doing work or the rate of energy transfer.

For comparison questions, first check whether work done is same or different, then compare time.

Simple machines are basic devices that make work easier by changing the size of force, direction of force, or distance over which force is applied.

In explanation questions, write what changes: force, distance, or direction. Do not say the machine creates work.