Force

Force

1. A push or a pull

   • Described by its strength and direction in which it acts
     • Strength and direction can be represented by an arrow which points in the direction of a force, and the length of the are shows the strength of the force, the longer the stronger
       • Strength measured in the SI unit called newton (N) named after Isaac Newton

2. Net force

   • The combination of all forces acting on an object
     • Determines whether an object moves and which direction it moves
   • Balanced forces
     • Equal forces acting on an object in opposite directions, there is NO net force
       • No change in the object's motion
   • Unbalanced forces
     • Whenever the forces on an object are unbalanced, there is A net force
       • Change in the object's motion

3. Friction

   • The force that two surfaces exert on each other when they rub against each other
     • The strength of the force of friction depends on two factors
       • How hard the surfaces push together
       • Types of surfaces involved
   • Four types of friction
     • Static Friction
       • Friction that acts on objects that are not moving
     • Sliding Friction
       • Two solid surfaces slide over each other
     • Rolling Friction
       • When an object rolls across a surface
     • Fluid Friction
       • When a solid object moves through a fluid

4. Gravity

   • A force that pulls objects towards each other
     • The strength of the gravitational attraction between objects depends on two factors
       • Mass
         • Measure of the amount of matter in an object
           • Weight is the force of gravity on a person or object on the surface of a planet
         • More mass greater gravitational pull
       • Distance
         • Less distance greater gravitational pull
   • Universal Gravitation
     • Law made by Newton that stated force of gravity acts between all objects in the universe
     • Isaac Newton
   • Free Fall
     • When the only force acting on an object is gravity, the object is said to be in free fall
     • In free fall the force of gravity is unbalanced, which causes an object to accelerate
       • All objects in free fall accelerate at the same rate regardless of masses
         • It does not seem like it because all objects falling through air experience air resistance
           • Air resistance is a fluid friction
       • Terminal Velocity
         • The greatest velocity a falling object reaches
   • Projectile
     • An object object that is thrown is called a projectile

5. Isaac Newton

   • Newton had three laws of motion
     • The Second Law of Motion
       • The second law states that acceleration depends on the object's mass and on the net force acting on the object
         • Acceleration= Net Force/ Mass
     • The Third Law of Motion
       • The third law states that if one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object
         • Basically meaning for ecery action there is an equal but opposite reaction
         • Momentum
           • What Newton called "quantity of motion", it is a characteristic of a moving object related to the mass and velocity of the object
             • Momentum=Mass x Velocity
           • Law of conservation of momentum
             • The total momentum of any group of objects remains the same, or is conserved, unless outside forces act on the objects
     • The First Law of Motion
       • The first law states that an object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force
         • This law is also called the law of inertia
           • Inertia is the tendency of an object to resist a change in motion
             • Inertia depends on mass

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