# what is force

Post on 01-Jul-2015

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• 1. What is Force?
• 1) Force is a push or pull
• 2) Force is the capacity to do work or cause physical change
• 3) Force= Mass times acceleration (F = ma)
• 4) A force is that which changes or tends to change the state of rest or motion of a body.

2.

• GROUPS OF FORCES:
• A. Contact Forces :
• 1. frictional force(friction)-
• caused by the rubbing of two objects.

3. 2. buoyant force(buoyancy)-it is the upward force of fluids on floating objects. 3. normal force-is the support force on an object which is in contact with another stable object. 4. air resistance force- type of frictional force upon objects as they travel through the air. 4.

• 5.Tension force- is the pulling force through a string, rope, cable or wire.
• 6.Spring force- is the force exerted by a compressed or stretched spring upon any object which is attached to it .
• 7.Applied force- is a force which is made to an object by a person or another object.

5.

• B. Action-at-a-distance forces:
• 1. gravitation-is the force with which the earth, moon, or other very large object attracts another object towards itself.
• 2. Electrostatic force is the force between particles that are caused by their electric charges.
• Electric force-
• 3.magnetic forces is the force made between magnetic poles

6.

• Common Units of Force
• --->> SI :Newton (N)1 N = 0.225 lb;
• One Newton (N) of force is defined as the amount of force needed to accelerate 1 kilogram (kg) of mass at a rate of 1 meter per second squared (m/s2).
• 1 Newton = 1 kg m/sec2(A kilogram is the amount of weight at which 1 N of force will accelerate at a rate of 1 m/s2.)

7.

• A force is avector quantity .
• Avector quantityis a quantity which has bothmagnitudeanddirection.
• Example:10 Newtons, downwards
• 25 km,east
• Ascalar quantitycan be described using only 1 quantity, magnitude.
• Examples:time, energy,volume,temperature.

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