O/A Level Physcs

Forces, work, energy and power POSTED IN O/A Level PHYSICS, MECHANICS Forces Forces are vectors, they have both a size (magnitude) and a direction. By adding up all the forces on an object like vectors you can find the resultant force which will tell you what will happen to the object. Forces can cause objects to accelerate and it makes logical sense that an object with more mass will accelerate less than an object with less mass when the same force is applied. This gives rise to an important equation: Where F is the force, m is the mass and a is the acceleration. This can be arranged to be more helpful: Work done Work is done when a force is used to move an object. If the direction of movement is the same as the direction of the force then work done can be calculated as: Where W is the work done, F the force and   is the change in displacement Work is measured in joules with 1J being equal to a force of 1 Newton moving an object 1 metre, therefore 1J = 1Nm (newton metre)

Vectors and scalars POSTED IN O/A Level PHYSICS, MECHANICS Contents Adding vectors Resolving vectors Scalar quantities are things like mass and speed, they only have a size. Vector quantities are things like velocity and acceleration, they not only have a size but also a direction such as 20ms -1  forward. Notation Vectors can be notated in several different ways:  - a vector from point a to b a - a vector called a, usually used in typed algebra a  - a vector called a, usually used in handwritten algebra Adding vectors Vectors can be represented b arrows with the length of the arrow representing the size of the vector (if drawn to scale). Vectors can be added by drawing them tip to tail and then finding the  resultant  of the vectors - the vector from the tail of the first vector to the tip of the last vector. A simple example: Here the resultant R is a single vector which could replace all the other vectors. If the drawing is to scale the size of the resultant can be measured

Describing motion POSTED IN O/A Level PHYSICS Blog, MECHANICS Contents Key terms Graphs Distance time graphs Displacement-time graphs Velocity-time graphs Motion can be described in multiple ways, using graphs, equations, words and symbols. This topic details some of the ways that you need to know about. Key terms Motion can be described using some key terms, symbols and units Name - symbol Description Units (standard) Speed - v Speed is the rate of travel, it is a scalar quantity so doesn't have a direction (it cannot be negative ms -1 Velocity -  v Velocity is the vector version of speed, the speed of an object in a given direction ms -1 Acceleration -  a Acceleration is the rate of change in velocity, therefore it too is a vector. Acceleration describes how many metres per second an object increases its speed each second hence the  -2  in the units. ms -2 Displacement -  s Displacement is the vector version of distance, it is the distance something has moved in

Projectiles POSTED IN PHYSICS, MECHANICS Contents Resolving the horizontal and vertical components Solving projectile questions Worked examples Projectiles are composed of two components: a vertical component and a horizontal component. Assuming there is no air resistance or friction the vertical acceleration is constant (9.81ms -1 , due to gravity) and the horizontal velocity is constant. The horizontal and vertical components act  independently ; they have no effect on one another. Resolving the horizontal and vertical components Resolving the horizontal and vertical components of a projectile is covered in full in the  vectors topic . To recap: The horizontal component,  A x  =  A  cos The vertical component,  A y  =  A  sin Solving projectile questions Projectiles are solved using the  kinematic equations . Projectile questions however require some thought, it's not usually as simple as plugging in some values into an equation, because of this they are a favourite in ex