Force- is a push or a pull. Newton- the strength of a force is measure in this SI unit. Net Force- the combination of all forces acting on an object. Unbalanced Forces- can cause an object to start moving, stop moving, or change direction. Balanced Forces- equal forces acting on one object in opposite direction. Friction- the force that two surfaces exert on each other when they rub against each other. Static Friction- the friction that acts on objects that are not moving. (sliding a desk across the floor - neither object is moving.) Sliding Friction- occurs when two solid surfaces slide over each other. (Brakes stopping a bike) Rolling Fiction- When an object rolls across a surface. Fluid Friction- occurs when a solid object moves through a fluid. (Machine parts move through oil - fluids.) Mass- a measurement of the same amount of matter in an object. Weight- the force of gravity on a person or object at the surface of a planet. (Are you heavier on earth or on the moon? Why?) Free Fall- when the only force acting against an object is gravity. Air Resistance- a type of fluid reaction that objects feel while falling through the air. (falling acorn vs. falling leaf) Terminal Velocity- the greatest velocity a falling object reaches. Projectile- an object that is thrown. Inertia- is the tendency of an object to resist a change in motion. (Moving forward when brakes are applied suddenly) Acceleration= net force/mass Momentum- is a characteristic of a moving object that is related to the mass and the velocity of a moving object. Momentum= mass x velocity
The unit for momentum is kg X m/sec. Conservation: Refers to the condition before and after an event. Satellite- any object that orbits another object in space. Centripetal Force- any force that causes an object to move in a circular path. Law of Universal Gravitation: States that the force of gravity acts between all objects in the universe.
REVIEW Page 344,45 for definitions Near the surface of earth, acceleration due to gravity is 9.8 m/s^2 NEWTON'S LAWS OF MOTION:
1) An object at rest will remain at rest and an object moving at a constant velocity will continue moving at a constant velocity unless it is acted upon by an unbalanced force. (The Law Of Inertia) (clothes on the ground, throwing a ball)
2) Acceleration depends on the mass and the on the net force acting on the object. Accelration = net force / mass. (Insert formula pg. 351) (tennis vs bowling ball; wagon -
3) If one object exerts a force on another object, than the second object exerts a force of equal strength in the opposite direction of the first object. For every action, there is an equal but opposite reaction. (jump - push the ground with your feet)
Key Concept: 1 - The Nature of Forces
Like velocity and acceleration, a force is described by its strength and by the direction which it acts.
Unbalanced forces acting on an object result in a net force and cause a change in the object's motion.
Balanced forces acting on an object do not change in the object's motion.
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The strength of the force of friction depends on two factors: how hard the surfaces push together and the types of surfaces involved.
Two factors affect the gravitational attraction between objects: mass and distance.
In free fall, the force of gravity is an unbalanced force, which causes an object to accelerate.
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An object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force.
Acceleration depends on the objects mass and on the net force acting on the object.
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If one object exerts a force on another object, then the second object exerts force of equal strength in the opposite direction on the first object.
The momentum of a moving object is equal to its mass times its velocity.
The total momentum of any group of objects remains the same, or is conserved, unless outside forces act on the objects.
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A rocket can rise into the air because the gases it expels with a downward action force exert an equal but opposite reaction force on the rocket.
Satellites in orbit around Earth continuously fall toward Earth, but because Earth is curved they travel around it.
Newton- the strength of a force is measure in this SI unit.
Net Force- the combination of all forces acting on an object.
Unbalanced Forces- can cause an object to start moving, stop moving, or change direction.
Balanced Forces- equal forces acting on one object in opposite direction.
Friction- the force that two surfaces exert on each other when they rub against each other.
Static Friction- the friction that acts on objects that are not moving. (sliding a desk across the floor - neither object is moving.)
Sliding Friction- occurs when two solid surfaces slide over each other. (Brakes stopping a bike)
Rolling Fiction- When an object rolls across a surface.
Fluid Friction- occurs when a solid object moves through a fluid. (Machine parts move through oil - fluids.)
Mass- a measurement of the same amount of matter in an object.
Weight- the force of gravity on a person or object at the surface of a planet. (Are you heavier on earth or on the moon? Why?)
Free Fall- when the only force acting against an object is gravity.
Air Resistance- a type of fluid reaction that objects feel while falling through the air. (falling acorn vs. falling leaf)
Terminal Velocity- the greatest velocity a falling object reaches.
Projectile- an object that is thrown.
Inertia- is the tendency of an object to resist a change in motion. (Moving forward when brakes are applied suddenly)
Acceleration= net force/mass
Momentum- is a characteristic of a moving object that is related to the mass and the velocity of a moving object.
Momentum= mass x velocity
The unit for momentum is kg X m/sec.
Conservation: Refers to the condition before and after an event.
Satellite- any object that orbits another object in space.
Centripetal Force- any force that causes an object to move in a circular path.
Law of Universal Gravitation: States that the force of gravity acts between all objects in the universe.
REVIEW Page 344,45 for definitions
Near the surface of earth, acceleration due to gravity is 9.8 m/s^2
NEWTON'S LAWS OF MOTION:
1) An object at rest will remain at rest and an object moving at a constant velocity will continue moving at a constant velocity unless it is acted upon by an unbalanced force. (The Law Of Inertia) (clothes on the ground, throwing a ball)
2) Acceleration depends on the mass and the on the net force acting on the object. Accelration = net force / mass. (Insert formula pg. 351) (tennis vs bowling ball; wagon -
3) If one object exerts a force on another object, than the second object exerts a force of equal strength in the opposite direction of the first object. For every action, there is an equal but opposite reaction. (jump - push the ground with your feet)
Key Concept:
1 - The Nature of Forces
- Like velocity and acceleration, a force is described by its strength and by the direction which it acts.
- Unbalanced forces acting on an object result in a net force and cause a change in the object's motion.
- Balanced forces acting on an object do not change in the object's motion.
2 -- The strength of the force of friction depends on two factors: how hard the surfaces push together and the types of surfaces involved.
- Two factors affect the gravitational attraction between objects: mass and distance.
- In free fall, the force of gravity is an unbalanced force, which causes an object to accelerate.
3 -- An object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force.
- Acceleration depends on the objects mass and on the net force acting on the object.
4 -- If one object exerts a force on another object, then the second object exerts force of equal strength in the opposite direction on the first object.
- The momentum of a moving object is equal to its mass times its velocity.
- The total momentum of any group of objects remains the same, or is conserved, unless outside forces act on the objects.
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