DYNAMICSTHE EFFECT OF FORCE

TYPES OF FORCE

MEASURING FORCE

FRICTION

ADVANTAGES AND DISADVANTAGES OF FRICTION

APPLICATION OF WORK

APPLICATION OF POWER

THE EFFECT OF FORCE

TYPES OF FORCETYPE OF FORCE EXPLANATION

FRICTIONAL FORCE Produced when two surfaces come into contact

GRAVITATIONAL FORCE Force of attraction that pulls objects towards the center of the Earth

ELECTROSTATIC FORCE Produced when two objects with different charges are brought near each other

MAGNETIC FORCE The attractive or repulsive forces exerted by magnets or other magnetic materials

ELECTRICAL FORCE Produced when electrons move through a conductor

MEASURING FORCE UNIT OF FORCE IS NEWTON (N) MEASURED USING A SPRING BALANCE

FRICTION Friction is a force that holds back the movement of a sliding

object.

You will find friction everywhere that objects come into contact with each other. The force acts in the opposite direction to the way an object wants to slide. If a car needs to stop at a stop sign, it slows because of the friction between the brakes and the wheels. If you run down the sidewalk and stop quickly, you can stop because of the friction between your shoes and the cement.

What happens if you run down the sidewalk and you try to stop on a puddle? Friction is still there, but the liquid makes the surfaces smoother and the friction a lot less. Less friction means it is harder to stop. The low friction thing happens to cars when it rains. That's why there are often so many accidents. Even though the friction of the brakes is still there, the brakes may be wet, and the wheels are not in as much contact with the ground. Cars hydroplane when they go too fast on puddles of water.

ADVANTAGES AND DISADVANTAGES OF FRICTION

Advantages of friction 1. It enables us to walk with out slipping. To enhance friction, it is

advisable to use shoes with rough sole while walking on slippery floors. For a similar reason, crutches are provided with rubber tips at their bottom to provide sufficient friction.

2. The breakers and tiers of our cars and bicycles depend on friction to function properly.

3. The ridges in the skin of our fingers and palms enable us to grasp and hold objects due to friction.

4. To prevent patients being uncomfortable in bed rubber sheets with spongy under surfaces are placed over mattresses. The friction between the spongy under surfaces and the mattress prevents the rubber sheet from slipping and wrinkling.

5. Nails and screws are held in wood by friction.

Disadvantages of Friction 1. Production of heat, noise and wear in machine parts rubbing against

one another. 2. Heat produce by friction may be sufficient to cause the abrasion of the

skin, resulting in friction burn. Rubber tubes such as gastric and duodenal tubes, rectal tubes and catheters may burn or irritate the membrane over which they pass unless measure are taken to prevent friction.

3. Friction reduces the efficiency of engine and other machines.

APPLICATION OF WORK Work done (joule/J) = Force (newton/N) x Distance

(meter/m)

APPLICATION OF POWER

Power (watt/W) = Work done (joule/J) Time (seconds/s)