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Gravity (also called weight) Friction Applied Force Air Resistance Tension Spring Force Normal Force (also called support force) http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/newtlaws/u2l2b.html#spring. Different Types of Forces. Gravity Tension Force Spring Force Applied Force
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Gravity (also called weight) Friction Applied Force Air Resistance Tension Spring Force Normal Force (also called support force) http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/newtlaws/u2l2b.html#spring Different Types of Forces
Gravity Tension Force Spring Force Applied Force Friction Air Resistance Normal force Force of attraction due to mass of an object Pulled force applied to a rope, wire or cable Elastic, compressed or stretched force Any push or pull on an object Resistance of two objects in contact moving past each other Resistance of an object moving through the atmosphere Force that pushes back on one object resting on another 2.3 Definition of Forces
2.3Support Force For an object at rest on a horizontal surface, the support force (normal force) must equal the object’s weight (gravity).
2.1Force Tension, Weight and Spring The upward tension in the string has the same magnitude as the weight of the bag, so the net force on the bag is zero. The bag of sugar is attracted to Earth with a gravitational force of 2 pounds or 9 newtons. Spring force (in scale) Tension (in string) • 1 lb = 4.45 N Weight (of bag) • 9 N of weight = 9 N of tension and spring force
2.3Support Force Support Force (also called normal force) The table pushes up on the book with as much force as the downward weight of the book. Fnorm = Fgrav Net force Weight (also called gravity)
2.3Support Force Physics The book lying on the table compresses atoms in the table and they squeeze upward on the book. The compressed atoms produce the support force.
2.3Support Force The upward support force is as much as the downward pull of gravity.
2.3Support Force The upward support force is as much as the downward pull of gravity.
2.3Support Force think! What is the net force on a bathroom scale when a 110-pound person stands on it?
2.3Support Force think! What is the net force on a bathroom scale when a 110-pound person stands on it? Answer: Zero–the scale is at rest. The scale reads the support force, not the net force.
2.3Support Force think! Suppose you stand on two bathroom scales with your weight evenly distributed between the two scales. What is the reading on each of the scales? What happens when you stand with more of your weight on one foot than the other?
2.3Support Force think! Suppose you stand on two bathroom scales with your weight evenly distributed between the two scales. What is the reading on each of the scales? What happens when you stand with more of your weight on one foot than the other? Answer: In the first case, the reading on each scale is half your weight. In the second case, if you lean more on one scale than the other, more than half your weight will be read on that scale but less than half on the other. The total support force adds up to your weight.
2.3Support Force For an object at rest on a horizontal surface, what is the support force (or normal force) equal to? • The object’s weight (or gravity)!
2.1Force Tension and Weight A stretched spring is under a “stretching force” called tension. Pounds and newtons are units of weight, which are also units of force. Weight is a force.