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Published byRonald Joseph Modified over 8 years ago
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1 st Law Law of Inertia
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An object at rest tends to stay at rest and an object in motion tends to stay in motion with a constant velocity and unless acted upon by an unbalanced force.
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Inertia can also be explained as an object’s resistance to change its motion. The greater the mass of an object, the greater its inertia.
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You placed your book bag in the trunk of your car. Which direction will your book bag slide if you suddenly hit the gas pedal? Why? Your book bag will slide backward because it was at rest initially and wanted to stay in that position even if the car moves forward.
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You placed a cake you bought on the passenger seat of your car. As you were driving down the street, a dog ran across the street in front of your car which caused you to slam on your breaks. What will happen to the cake? Why? The cake will slide forward off the seat because it was initially moving forward and wanted to keep moving forward even if the car stopped.
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When all the forces acting upon an object balance each other, the object will be at equilibrium; it will not accelerate. When an object experiences forces that do not balance each other, the object will accelerate.
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A force is a push or pull upon an object resulting from the object’s interaction with another object.
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Applied force (F app ) – a push or pull on the object by another object. Force of gravity (F g ) - force with which the earth or other massive body attracts an object towards itself. It is the weight of the object. Normal force (F N ) = support force exerted upon an object which is in contact with another stable object. Surface force
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Friction force (F f ) - force exerted by a surface as an object moves across it. It opposes the motion of the object. Air resistance force (F air ) – force which acts upon objects as they travel through the air. Tension force (F tens ) - force which is transmitted through a string, rope, or wire when it is pulled Spring force (F spring ) - force exerted by a compressed or stretched spring upon any object
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To be done on the white board.
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One Newton is the amount of force required to give a 1-kg mass and acceleration of 1 m/s 2. Unit of measure: N or kg·m/s 2
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If the forces are acting in the same direction, you need to add the forces together. If the forces are acting in opposite directions, you need to subtract the lesser force from the greater force. If the forces are perpendicular to each other, use the Pythagorean Theorem.
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If net force is zero, the object is either at rest or moving at a constant velocity. If the net force is not zero, the object is acceleration which means velocity is changing.
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Practice Problems
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