# whether contect forces act in action and reaction pair.coment on the basis of friction force.

SAGAR SINGH - IIT DELHI
879 Points
12 years ago

Dear student,

Balanced forces are equal forces that are applied in opposited directions and result in no change in velocity. Unbalanced forces are forces that are not equal and opposit and result i a change in velocity. A unit that's commonly used to describe forces we feel is the "g". One"g" is equal to the force of earth's gravity. When the space shuttle takes off, the astronauts feel about 3 g's of force (three times the force of the earth's gravity). If a body, for examle a roller coaster, is standing still it won't want to move unless some contact force pushes or pull sit. This resistance of the roller coaster is called inertia. The more mass a body has the more inertia it has. If the roller coaster is moving, it will want to keep moving, along the direction the direction of motion unless some thing causes it to speed up or slow down. This resistance of the moving roller coaster to change its velocity is also another example of its inertia. Work is a force used to move something in the direction of the force. Kind of hard to explain but if you hold a box, no work is being done to the box. If you drag a box, then work is being done. Work is how much you have to push or pull a roller coaster in order to move it force a certain distance. Work is done if a chain, pulled by a motor, pulls the coaster up to the top of a hill on the track. It takes work to lift a roller coaster to the top of the first hill in order to over come the first hill in order to overcome the force of gravity. The more mass a coaster has, the more work is required to pull it to the top. The further the roller coaste must climb, the more work is done to get the coaster to the top of the hill. These are just a few of the many everyday forces a roller coaster uses and overcomes, to give you the best 2.5 minute ride of your life.

All the best.

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