Work-Energy Theorem - SS1 Physics Lesson Note

The work-energy theorem is a fundamental principle in physics that relates the work done on an object to the change in its kinetic energy. It states that the net work done on an object is equal to the change in its kinetic energy. Mathematically, the work-energy theorem can be expressed as:

Net Work (Wnet) = Change in Kinetic Energy (ΔKE)

The work done on an object can be calculated using the formula:

Work (W) = Force (F) x Displacement (d) x cosθ

where F is the magnitude of the force applied, d is the displacement of the object, and θ is the angle between the force and displacement vectors.

The change in kinetic energy can be calculated using the formula:

ΔKE = KEfinal - KEinitial

where KEfinal is the final kinetic energy of the object and KEinitial  is the initial kinetic energy.

According to the work-energy theorem, if the net work done on an object is positive, it means that work is being done on the object, resulting in an increase in its kinetic energy. This corresponds to an acceleration or an increase in speed. Conversely, if the net work done on an object is negative, it means that work is being done by the object, resulting in a decrease in its kinetic energy. This corresponds to a deceleration or a decrease in speed.

The work-energy theorem is a powerful tool for analysing and understanding the relationship between work and energy. It allows us to determine how the work done on an object affects its kinetic energy and, consequently, its motion. This principle is widely applied in various areas of physics, such as mechanics, thermodynamics, and electromagnetism. It provides insights into the energy transformations and transfers that occur in physical systems and is instrumental in solving problems related to motion, forces, and energy.