domingo, 29 de agosto de 2010

How levers work

simple machine:a divice with few parts that makes it easier to do work

effort force: the force applied to a machine



resistance force: the force that a machine acts against


lever: a simple machine made of  a rigid bar on a pivot point



fulcrum: the pivod point of a lever


machanical advantages:the number of times a machine multiplies the force applied



pulley: a grooved wheel that turns by the action of a rope in the groove



wheel and axle: a simple machine made of a handle or axis attached to the center of a wheel


Energy and Work

Potential energy:the energy stored in an object or material










gravitational potential energy: the potential energy of an object located above the ground

kinetic energy: the energy of an moving object



work: force applied to an object times the distance the object moves









domingo, 22 de agosto de 2010

Foreces and Newton´s first Law (vocabulary # 1)

Force:a push or pull exerted by one object on another









Friction:a force that opposes the motion of an object in  contact with the surface














drag force:a force that oppose the motion of and object through a liquid or gas.

 
 gravity:a force of attraction that exist between all object with mas


 












net force:the combined effect  of all the forces acting on an object


balanced force: forces that cancel each other out when acting together on a single object


unbalanced force: forces that do not cancel each other out when acting together on a single object


inertia:the tendency of an object to oppose a change in motion



momentum: the mass of an object multiplied by its velocity