A Level Maths - Mechanics

What is a particle and what are its modelling assumptions

• Particle - dimensions are negligible,

• Assumptions - the mass of the object is concentrated at a single point and that rotational forces and air resistance can be ignored

What is a rod and what are its modelling assumptions

• Rod - All dimensions but one are negligible (pole)

• Assumptions - mass is concentrated along a line, no thickness and rigid

What is a laminate and what are its modelling assumptions

• Lamina - object with area but negligible thickness (sheet of paper)

• Assumptions - mass is distributed across a flat surface

What is a uniform body and what are its modelling assumptions

• Uniform body - Mass is distributed evenly

• Assumptions - Mass of the object is concentrated at a single point at the geometrical centre of the body - the centre of mass

What is a light object and what are its modelling assumptions

• Light object - Mass of the object is small compared to other masses (string / pulley)

• Assumptions - treat object as having 0 mass, tension the same at both ends of a light string

What is an inextensible string and what are its modelling assumptions

• Inextensible string - a string that does not stretch under load

• Assumptions - acceleration is the same in objects connected by a taut inextensible string

What is a smooth surface and what are its modelling assumptions

• Smooth surface - what it says on the tin mate

• Assumptions - there is no friction between the surface and any object on it

What is a rough surface and what are its modelling assumptions

• Rough surface - again what it says on the tin

• Assumptions - objects in contact with the surface experience a frictional force if they are moving or are acted on by a force

What is a wire and what are its modelling assumptions

• Wire - rigid thin length of metal

• Assumptions - treat as one-dimensional

What is a smooth and light pulley and what are its modelling assumptions

• Smooth and light pulley - all pulleys you consider will smooth and light

• Assumptions - pulley has no mass, tension is the same on either side of the bead

What is a peg and what are its modelling assumptions

• Peg - a support from which a body can be suspended or rested

• Assumptions - dimensionless and fixed, can be rough or smooth question will specify

What is air resistance and what are its modelling assumptions

• Air resistance - resistance experienced as an object moves through the air

• Assumptions - usually modelled as being negligible

What is gravity and what are its modelling assumptions

• Gravity - force of all attraction between all objects

• Assumptions - all objects with mass are attracted towards the Earth, Earths gravity is uniform and acts vertically downwards, 9.8 metres per second squared

On a displacement-time graph what does the gradient represent?

Velocity

On a velocity-time graph what does the gradient and area under the graph represent?

• Gradient = acceleration

• Area under graph = displacement