SPH4U-C

4.1 Work Done By a Constant Force - W = (F cos q )d (Joules) - q is the angle between the force and the displacement, d is the magnitude of the displacement - negative work and zero work

4.2 Kinetic Energy and the Work-Energy Theorem - kinetic energy is the energy of motion - Ek = ½ mv2 - total work done on an object equals the change in the object’s kinetic energy, provided there is no change in any other form of energy (i.e. gravitational potential energy)

4.3 Gravitational Potential Energy at the Earth’s Surface - Ep = mgy (Joules) – y is the vertical component of the displacement

4.4 Law of Conservation of Energy - for an isolated system, energy can be converted into different forms, but cannot be created or destroyed - applications - other forms of energy (thermal, etc)

4.5 Elastic Potential Energy and Simple Harmonic Motion - Hooke’s law: Fx = -kx - the magnitude of the force exerted by a spring (or an elastic device) is directly proportional to the distance the spring has moved from equilibrium, where k is the force constant - An ideal spring obeys Hooke’s law since it has little or no internal or external friction - elastic potential energy: Ee = ½ kx2 - simple harmonic motion: period (T – in seconds) = 2 pÖ (m/k) – m is the mass of the object oscillating and k is the force constant of the spring - energy in simple harmonic motion and damped harmonic motion

5.1 Momentum and Impulse - linear momentum p = mv (instantaneous velocity), is a vector quantity (can be split into components) - impulse is a force applied over a period of time (unit is N s), which is equal to the change in momentum (Ft = p), since these are vector quanties: Fxt = px and Fyt = py - net force on an object equals the rate of change of an object’s momentum

5.2 Conservation of Momentum in One Dimension - Law of conservation of linear momentum: if the net force acting on a system of objects is zero, then the linear momentum of the system before the interaction equals the linear momentum of the system after the interaction. - During an interaction between two objects in a system on which the total net force is zero, the change in momentum of one object is equal in magnitude, but opposite in direction to the change in momentum of the other object. - For any collision involving a system on which the total net force is zero, the total momentum before the collision equals the total momentum after the collision

5.3 Elastic and Inelastic Collisions - elastic collision: a collision in which the total kinetic energy after the collision equals the total kinetic energy before the collision - inelastic collision: a collision in which the total kinetic energy after the collision is different from the total kinetic energy before the collision (extreme case completely inelastic collision happens when objects stick together when they collide). - newton’s cradle - solving collision problems

5.4 Conservation of Momentum in Two dimensions - collisions in two dimensions are analyzed using the same principles as collisions in one dimension: conservation of momentum for all collisions for which the net force on the system is zero, and both conservation of momentum and conservation of kinetic energy if the collision is elastic.