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Chapter 14: Interactions through the application of forces - Coggle Diagram
Chapter 14: Interactions through the application of forces
Type of forces
Non-contact forces(force that acts on a subject without touching it)
Gravitational force (force that attracts objects to planets)
Ocean tides: tides on earth caused partly by moon's gravity pulling on the waters of the oceans
Weight :the force of gravity(weight) keeps us seated in our chairs
Electrostatic force: hair on our arms and dust on the table are attracted to plastic wrap because of electrostatic forces. electric charge can be negative or positive
Magnetic force: force exerted by a magnet on magnetic materials such as iron and steel. every magnet has a North pole and a South pole.
Contact forces: Friction(force that acts on two materials rubbing together)
Walking : when we walk, the rough soles of feet (or shoes) rub against the ground. We depend on friction between our feet and the ground to push our body forward.
Parachuting : parachutists use friction between falling objects and the air. Parachute is a large piece of nylon that produces a large frictional force with the air. Force reduces the speed of parachutist's fall.
Force: a push or a pull
Measuring force( SI unit is newton (N))
Instructional for measuring force
Compression spring balance: the spring in a compression spring is compressed when a pushing force acts on it
Extension spring balance: the spring in an extension spring balance stretches when a pulling force acts on it.
In both types, a pointer attached to the spring indicates the amount of force acting on the pring
Mass and weight : the force of gravity(weight) is different massive objects. the weight of a person on earth is greater than his weight on the moon. this is due to the stronger gravity on earth.
Mass on earth= 60kg Weight on earth=600N
Mass on moon=60kg Weight on moon =100N
Effect of Forces
Effects of forces on the size or shape of an object: when we apply a force on an object, its physical dimensions may change
When we mould a lump of wet clay, the size and shape of the shape of the object changes
When we apply a force to knead a lump of plasticine, the shape of the object changes
Squeezing a tube of toothpaste: our fingers press on a tube to squeeze out toothpaste
Pressing a button in a lift : we use our fingers to press lift buttons
Opening a window or a door: our hands touch the handle of a window or door to push or pull it open
Speed : the distance travelled per unit time
Speed=distance travelled/ time taken
Turning effect of forces on an subject: the force produces a turning effect on the door, causing it to open. By applying a force to one point of a lever, we overcome the turning effect of another force
Pressure: an effect of a force acting on an object. it depends on the amount of force and the area on which the force acts.
When the force acting on a surface decreases, the pressure decreases. When the area if the surface increases, the pressure decreases
Pressure in everyday life
Spikes on soles of football shoes have small shoes. the large pressure produced by the spikes increases the shoes grip on the ground
Stiletto heels often leave unsightly marks on carpets. the weight of the wearer exerts a large pressure on a small area of ground
Pressure in liquids
Water supply: water is delivered and stored in a tank on top. this causes water in the pipes below the tank to be at a high pressure. the high water pressure ensures that water flows to the units below.
Submarines: the rigid body of submarines withstands the very high pressure deep underwater. if it dives beyond a certain depth, the pressure may become too high and damage the submarine
Atmospheric pressure
By sucking through straw, we lower the air pressure in the straw. the higher atmospheric pressure outside the straw pushes the liquid up the drinking straw.