Forces

• Vectors have magnitude and direction
• Forces can be contact or non-contact
• Contact forces: Friction, air resistance, tension, torsion, normal force, gravitational force
• Non-Contact Forces: Magnetic force Electrostatic force Gravitational force
• Gravitational Force is the force attraction between masses
• Weight and Mass are not the same
• Mass is the amount of stuff in an object
• Weight is the force acting on the object due to gravity
• Mass and Weight are directly proportional
• Weight= Mass x Gravitational Field Strength
• Gravitational Field Strength on earth is 9.8 N/Kg
• Free body diagrams show all the forces acting on object
• Resultant Force is the overall force acting on an object
• If a resultant force moves an object, work is done
• An object is in equilibrium is the forces are balanced
• Stretching, Compressing or Bending an object transfers energy
• Extension is directly proportional to Force
• A moment is the turning effect of a force
• A larger force or longer distance is a larger moment
• Levers increase the distance from the pivot meaning less force is needed for the same moment
• Gears transmit rotational effects
• A larger gear causes a larger moment
• Pressure is the force per unit area
• Pressure in liquids depend on depth and density
• Objects in a fluid experience upthrust
• An object will float if its weight=upthrust
• Atmospheric pressure decreases with height
• Distance is scalar, displacement is a vector
• Speed is scalar, velocity is vector
• Acceleration is how quickly you speed up or slow down. It is measured in metres per second squared (m/s2)
• Uniform acceleration is a constant acceleration
• Friction always slows things down
• Drag increases as speed increases
• Objects falling through fluids reach a terminal velocity
• Terminal velocity=maximum velocity
• Terminal Velocity depends on shape and area
• Air resistance causes things to fall at different speeds
• A force is needed to change motion
• Inertia is the tendency of an object to remain stationary or continue moving with constant velocity unless acted upon by a net external force.
• The greater the mass, the more inertia it has