Download MOTION, FORCES, AND WORK

FORCES AND WORK
Vocabulary and Notes
Vocabulary
1. Force: a push or pull
2. Net force: the overall force on an object when all the individual forces acting on an object are
added together
3. Unbalanced forces: a nonzero net force, which changes and object’s motion
4. Balanced forces: equal forces acting on an object in opposite directions
5. Inertia: the tendency of a object to resist a change in its motion
6. Mass: the amount of matter in an object
7. Friction: the force that one surface exerts on another when the two rub against each other
8. Gravity: the force that pulls objects toward each other
9. Air resistance: the friction experienced by objects falling through the air
10. Weight: the force of gravity on an object at the surface of a planet
11. Work: Force exerted on an object that causes it to move.
12. Joule: a unit of work equal to one Newton-meter
13. Machine: a device that changes that amount of force exerted or the direction in which force is
exerted
14. Fulcrum: the fixed point around which a lever rotates
15. Compound machine: a device that combines two or more simple machine
(Forces)
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The sum of all the forces acting on an object is the net force.
Unbalanced forces change the motion of an object, whereas balanced forces do not.
Friction is a force that one surface exerts on another when they rub against each other.
The force of gravity acts between all objects in the universe.
Weight is a measure of the force of gravity on an object, and mass is the amount of matter that
an object contains.
(Work)
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Work is done on an object when a force causes that object to move a distance.
The amount of work done on an object is equal to the force on the object in the direction of its
motion multiplied by the distance the object moves.
Work = Force X Distance
A machine makes work easier by changing the direction of or the amount of force needed to
accomplish a task.
There are six basic kinds of simple machines: the inclined plane, the wedge, the screw, the
lever, the wheel and axle, and the pulley.
A compound machine is a machine that is made from two or more simple machines.