Exam Questions - Work, energy and power

Exam Questions - Work, energy and power

Section 1: Understanding Work

• Grasp the concepts of displacement, force, and angle to compute the work done by a force.
• Remember that work is the dot product of force and displacement i.e. Work = Force x displacement x cos(angle).
• Cognize work as a scalar quantity, meaning it has magnitude but no direction.

Section 2: Energy

• Learn that kinetic energy is the energy of motion and is calculated as 1/2 m v² where m is mass and v is velocity of the object.
• Understand that potential energy is the energy an object possesses because of its position or configuration. Gravitational potential energy is calculated as m g h where m is mass, g is gravitational acceleration, and h is the height.
• Recognise that energy is always conserved. In an isolated system, the total energy (kinetic + potential) remains constant.

Section 3: Power

• Interpret power as the rate of doing work or the rate of transfer of energy.
• Remember the formula P = W/t where P is power, W is work done and t is time taken.
• Know that power is also calculated as P = F v cos(θ) where F is force, v is velocity and θ is the angle between the force and velocity vectors.
• Understand the units of power which is watts (W).
• Bear in mind that power is a scalar quantity.

Section 4: Problem-Solving Techniques

• Master the skill of drawing diagrams representing the physical situation of a problem. Include object’s velocities, forces, and positions.
• Always break down forces and displacements into components when the angle is other than 0 or 90 degrees.
• Use energy principles (conservation of mechanical energy) to solve problems involving work, energy and power.
• Be comfortable with simple calculus as work, energy and power equations often need integration or differentiation to solve.
• Practise plenty of past paper questions to gain proficiency in problem-solving within the time limit.