Chapter F1 - Force and Pressure

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Chapter F1 - Force and Pressure

1. FORCE

1.3. Examples of FORCES

1.3.1. Frictional Force (Friction)

1.3.1.1.1. There is friction between two moving objects when they are in contact with each other.

1.3.1.1.2. Slows down and/or stops a moving object

1.3.1.1.3. Produces heat

1.3.1.2.1. Makes movemnt more difficult

1.3.1.2.2. Causes wear and tear

1.3.1.3. Ways to reduce friction

1.3.1.3.1. Using smooth surfaces

1.3.1.3.2. Lubrication

1.3.1.3.3. Ball bearings

1.3.1.3.4. Streamlining

1.3.2. Magnetic Force

1.3.2.1. A magnet can attract objects made of steel, iron, nickel and cobalt.

1.3.2.2. Forces between magnets

1.3.2.2.1. A magnet has 2 poles - North pole and South pole

1.3.2.2.2. Like poles repel (push) while unlike poles attract (pull).

1.3.3. Gravitational Force (Gravity)

1.3.3.1. Pulls objects to the center of the Earth.

1.3.3.2. Exists between any two objects.

1.3.4. Weight

1.3.4.1. The weight of an object depends on the force of gravity pulling on that object.

1.3.4.2. An object is heavier when the force of gravity pulling on it is greater.

1.3.4.3. Measured using a spring balance and it is measured in Newtons.

3. How do we measure a force?

3.1. Force-meters

3.1.1. Spring balances

3.1.1.1. Extension spring balance

3.1.1.2. Compression spring balance

4. PRESSURE

4.5. Calculating Pressure

4.5.1. Pressure = Force/Area

4.5.2. SI Unit: Pascal (Pa)

4.5.3. Sample Question: An elephant stands on one foot, and the lady stands on one stiletto heel, but the lady's heel exerts more pressure than the elephant's foot. Why is this so? Answer: The force exerted by the elephant's foot and the lady's stiletto heel is the same, but because the lady's stiletto heel is smaller than the elephant's foot, the surface area in contact with the lady's stiletto heel is smaller, hence the pressure exerted is higher.