Physics Year 9 no.3

• If the upthrust and weight are balanced, will the object sink of float?

  Float
• If the weight is greater than the upthrust, will the object sink or float?

  Sink
• What increases with depth in a liquid?

  Pressure
• Forces are measured in newtons and cause changes to an objects motion or shape
• What is weight?

  The force acting on an object due to pull of gravity from a massive object
• What is the equation for weight?

  Weight (N) = mass (kg) x gravitational field strength (N/kg)
• A resultant force is the single force that has the same effect as 2 or more forces acting together
• What do elastic materials do after being stretched or squashed?

  Return to their original shape and size
• Inelastic materials do not return to their original shape and size after being stretched or squashed
• For an elastic object, force is directly proportional to extension
• Stretched objects store what?

  Elastic Potential Energy
• What is the equation for an elastic object?

  Force (N) = Spring constant (N/m) x extension (m)
• Elastic Potential Energy (J) = $\frac{1}{2}$ x Spring constant x extension$^2$
• What is the center of mass?

  The point where all weight appears to act
• What is a moment?

  It is the turning effect of a force
• What is the equation for moment?

  Moment (Nm) = Force (N) x perpendicular distance from pivot (m)
• In a Hydraulic system a force is transmitted through a liquid between two pistons, the pressure in the liquid is constant, so the force can be INCREASED by DECREASING the area of the SECOND piston
• The higher the amplitude, the higher the sound
• The Higher the frequency, the higher the pitch