Modelling In Mechanics Flashcards
What force acts downward on an object?
Weight (or gravitational force)
What forces act upwards on an object?
Normal reaction, up thrust, buoyancy
Which force opposes the motion between two rough surfaces?
Friction
If an object is being pulled along by a string what force is acting on it?
Tension
What force opposes motion but is not between two rough surfaces?
Air resistance
If an object is pushed along using a light rod what is the force called?
Thrust or compression
What assumptions are made when describing an object as a particle?
The mass of the object is concentrated at a single point. Rotational forces and air resistance can be ignored.
What assumptions are made when describing an object a rod?
Mass is concentrated along a line. No thickness. It is rigid.
What assumptions are made when describing an object as a lamina?
Mass is distributed across a flat surface.
What assumptions are made when an object is described as a uniform body?
Mass of the object is concentrated at a single point at the geometrical centre of the body.
What assumptions are made when describing an object as a light object?
Treat the object as having 0 mass.
Tension is the same at both ends of a light string.
What assumptions are made when describing an object as an inextensible string?
Acceleration is the same in objects connected by a taut inextensible string.
The string cannot stretch under load.
What assumptions are made when describing a surface as smooth?
Assume there is no friction between the surface and any object on it.
