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CHPT 9: Forces, Non-contact force - Coggle Diagram

- - - - Hammers
      - Fishing rods
- - - - Do not use definition as a type of error!!!
- - - - Pressure = Force / Area
  - - - It needs to be very sharp so that the area of contact of the needle with the skin is very small. When we apply a force on the needle, a high pressure allows the sharp needle to pierce the skin easily.
    - - It has a smaller area of contact with a surface than the heel of a sneaker. If a woman wearing high-heeled shoes steps on a mobile phone screen, the screen will likely crack due to the high pressure exerted on it.
    - - It has a smaller area of contact with a tomato that a blunt knife. With the same amount of force applied, a sharp knife exerts a higher pressure than a blunt knife. Thus, it is able to cut the tomato more easily
    - - Dam
        
        The base of it has a much thicker wall than its top. This is because water pressure is higher at the base of it and a thicker wall is better able to withstand the high pressure
      - Submarine
        
        Submarine dive to great depths underwater. The pressure deep below the water surface can be very high. Hence, a submarine needs a strong body to withstand this high pressure.
    - - definition
        
        Earth is surrounded by a thick layer of air. Air particles are light, occupy space and have mass. When the layer of air particles pushes down on Earth's surface due to gravitational force, it exerts a pressure of approximately 100 000 Pa at the sea level.
        
        When we are at a height above the sea level, fewer air particles push down on us. Hence, the atmospheric pressure exerted on us decreases.
- - - - Ways to reduce friction
        
        Smooth surfaces/textures
        
        ball bearings
        
        lubricants/oil/grease
        
        streamlined shape
      - Friction is used when
        
        Helps in walking and standing stably
        
        Helps writing on paper
        
        Helps to light up a match
        
        Reduces the speed of parachutists
      - Definiton
        
        Friction is the force that opposes the motion between two surfaces in contact
      - Examples
        
        Wear and tear on the soles of shoes
        
        Rolling a bowling ball
      - Friction as a nuisance
        
        Makes movement difficult
        
        Causes wear and tear
    - - Examples
        
        Stretching a rubber band
        
        Pressing a ball filled with air
        
        jump rope
        
        spring
        
        bow
        
        bungee jump
      - Definition
        
        Elastic force is the force acting on a stretched or compressed elastic object to return to its original shape
- - - - Rain falling from the sky to the ground
      - Playing badminton
      - Playing rugby
    - - Force that attract two objects towards each other
    - - pull only!!
      - depends on
        
        mass
        
        location
    - - allow us to stand/ walk stably on ground without floating
      - Motion of the planet in solar system is controlled by gravity
      - Give object weight
      - Causes tides in the ocean
      - Keep artificial satelites in their orbits
  - - - Refrigerator doors are kept close tightly
      - separate magnetic and non-magnetic materials
        
        iron and plastic
        
        can be taken out with magnet
        
        iron and steel
        
        cannot be taken out with magent
        
        reason
        
        both are magnetic materials
        
        iron and aluminium
        
        can be taken out with magnet
      - Maglev train
    - - The force exerted between a magent and another magentic materials such as iron and steel & exists between two magents
    - - both push and pull!!!
      - depends on the poles of the magnet & presence of the magnetic materials