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18 Cards in this Set
- Front
- Back
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Newton's First Law of Motion
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The velocity of an object will not change unless the object is acted on by an outside force. This is otherwise known as the law of inertia.
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In the absence of friction, how long will an object traveling at 8 m/sec continue in motion?
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It will continue traveling indefinitely at 8m/sec in a straight line until some other force acts upon it.
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inertia
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The tendency of an object to resist changes in its velocity.
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If a car is rear-ended, which direction do the occupants move in first?
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Backward, into the seats. This is why there are head rests on seats, to prevent your head from snapping backward too far in a rear-end situation.
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If a car is in a head on collision, which way do the occupants move first?
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They move forward, continuing in the direction they were moving before their vehicle (but not the occupants) stopped moving.
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friction
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a force that opposes motion, resulting from the contact of two surfaces.
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What is responsible for friction?
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On an up-close level, surfaces are not smooth, and "hang-up" on each other when they try to move in opposite directions.
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What do we call the type of friction that interferes with a true "free-fall" situation near the surface of the earth?
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air resistance.
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Newton's Second Law of Motion
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When an object is acted on by one or more outside forces, the total force is equal to the mass of the object times the resulting acceleration.
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total force
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mass X acceleration
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Newton (unit)
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the standard unit of force.
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Total force (for an object being slid on the ground)
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Force of push - Force of friction
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Kinetic friction
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Friction that opposes motion once the motion has already started
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Static friction
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Friction that opposes the initiation of motion
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Which is generally greater, kinetic or static friction?
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Static friction is usually greater.
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If a box is already moving at a constant velocity, and the kinetic friction is 10 Newtons, how much force must be applied to keep it moving at a constant velocity?
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An amount equal to the kinetic friction, or 10 Newtons, must be applied. This makes the total force 0 Newtons, which would keep the velocity constant (Newton's first law) with no acceleration.
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Newton's Third Law
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For every action, there is an equal and opposite reaction.
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In Newton's Third Law, do the force and the equal and opposite force act on the same object?
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No, they act on different objects. If they acted on the same object, nothing would move because the forces would cancel each other out, and there would be no total force, and therefore, no acceleration.
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