RECURSOS DELS CURSOS

llibres química

jgalla2 — Tue, 26 Apr 2011 08:55:32 +0000

Newton’s laws of motion

jgalla2 — Wed, 10 Nov 2010 17:39:27 +0000

The three laws of motion on which Newtonian mechanics is based. (1) A body continues in a state of rest or uniform motion in a straight line unless it is acted upon by external forces. (2) The rate of change of momentum of a moving body is proportional to and in the same direction as the force acting on it, i.e. F = d(mv)/dt, where F is the applied force, v is the velocity of the body, and m its mass. If the mass remains constant, F = mdv/dt or F = ma, where a is the acceleration. (3) If one body exerts a force on another, there is an equal and opposite force, called a reaction, exerted on the first body by the second.

parallelogram of vectors

jgalla2 — Tue, 09 Nov 2010 12:46:36 +0000

A method of determining the resultant of two vector quantities. The two vector quantities are represented by two adjacent sides of a parallelogram and the resultant is then the diagonal through their point of intersection. The magnitude and direction of the resultant is found by scale drawing or by trigonometry. The method is used for such vectors as forces (parallelogram of forces).

llei de hook

jgalla2 — Mon, 08 Nov 2010 17:45:04 +0000

Hooke’s law
The stress applied to any solid is proportional to the strain it produces within the elastic limit for that solid. The ratio of longitudinal stress to strain is equal to the Young modulus of elasticity. The law was first stated by Robert Hooke in the form ‘Ut tensio, sic vis.’