My notes

• Vector


  A physical quantity that has both magnitude and direction
• Scalar


  A physical quantity that has magnitude only
• Resultant vector


  The single vector which has the same effect as the original vectors acting together
• Distance


  The length of path travelled
• Displacement


  A change in position
• Speed


  The rate of change of distance
• Velocity


  The rate of change of position or the rate of displacement
• Acceleration


  The rate of change of velocity
• Weight (Fg)


  The gravitational force the Earth exerts on any object on or near its surface (Fg = mg)
• Normal force (FN)


  The perpendicular force exerted by a surface on an object in contact with it
• Frictional force due to a surface (Ff)


  The force that opposes the motion of an object
• Newton's first law


  An object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force
• Inertia


  The property of an object that causes it to resist a change in its state of rest or uniform motion
• Newton's second law


  When a net force, Fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass
• Newton's third law


  When object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A
• Linear Momentum


  The product of the mass and velocity of the object (p = mv)
• Newton's second law in terms of momentum


  The net force acting on an object is equal to the rate of change of momentum (Fnet = ∆p/∆t)
• Law of conservation of linear momentum


  The total linear momentum of an isolated system remains constant (is conserved)
• Elastic collision


  A collision in which both momentum and kinetic energy are conserved
• Inelastic collision


  A collision in which only momentum is conserved
• Impulse (J)


  The product of the net force and the contact time (J = Fnet∆t)
• Work done on an object by a force


  The product of the displacement and the component of the force parallel to the displacement (W = Fs or W = F∆x or W = F∆xcos𝜃)
• Gravitational potential energy


  The energy an object possesses due to its position relative to a reference point (Ep = mgh)
• Kinetic energy


  The energy an object has as a result of the object's motion (EK = 1/2 mv2)
• Mechanical energy


  The sum of gravitational potential and kinetic energy at a point (EM = Ep + EK)
• Law of conservation of energy


  The total energy in a system cannot be created nor destroyed; only transferred from one form to another
• Principle of conservation of mechanical energy

  In the absence of air resistance or any external forces, the mechanical energy of an object is constant (Ep + EK)i = (Ep + EK)f
• Work-energy theorem


  The work done by a net force on an object is equal to the change in the kinetic energy of the object (Wnet = ∆EK)
• Power


  The rate at which work is done or the rate at which energy is transferred (P = W/t)
• One Watt


  The power when one joule of work is done in one second
• Efficiency


  The ratio of output power to input power (% efficiency = powerout/powerin x 100)
• Newton's law of universal gravitation


  Every particle with mass in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres (F = G m1m2/r2)
• Weight (Fg)


  The gravitational force the Earth exerts on any object on or near its surface
• Gravitational field


  The force acting per unit mass (g = F/m)
• Coulomb's law


  Two point charges in free space or air exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between the charges (F = k q1q2/r2)
• Magnitude of electric field at a point

  The force per unit positive charge (E = F/q where E and F are vectors)
• Potential difference


  The work done per unit positive charge (V = W/Q)
• Current


  The rate of flow of charge (I = q/t)
• Ohm's law


  Current through a conductor is directly proportional to the potential difference across the conductor at constant temperature
• Resistance


  A material's opposition to the flow of electric current