# Year 8 Forces & Formulae Learning Objectives Pupils should know:

• Be able to identify formulae and equations
• Label terms in an equation
• Manipulate equations to change ‘the subject’
• Understand the terms commensurate and incommensurate units
• Identify base units and derived units
• Use prefixes and be able to convert units from one form to another
• Use the homogenous nature of meaningful physical equations to derive unit
• Be able to define and identify vectors and scalars
• Be able to add and subtract vectors through the use of diagrams
• The difference between thinking distance and braking distance and factors that affect each.
• Be able to plot distance – time graphs
• Be able to calculate the speed from the gradient of a distance – time graph
• That acceleration is the rate of change of speed (velocity)
• Be able to plot speed time graphs
• Be able to calculate the distance travelled from the area under a speed time graph
• Describe how the forces acting on an object falling at terminal velocity are balanced
• That the area over which a force acts is important
• Pressure = Force ÷ Area
• That pressure is measured in Pascals (Pa) or N/m2 or N/cm
• How to convert N/cm2 to N/m2
• Applications of high and low pressure
• That solids transmit force but fluids (liquids and gases) transmit pressure
• That in liquids:
a. Pressure increases with depth
b. Pressure acts equally in all directions
c. Pressure is the same at any depth
• How hydraulics use pressure
• That a force may cause an object to rotate or turn about a point called a pivot
• That the turning effect of a force is called the moment of the force
• That the size of the turning effect depends upon the size of the force and the distance of the force from the pivot
• Moment = force x distance to pivot
• Moment is measured in units Nm or Ncm
• That a moment may cause an object to rotate clockwise or anticlockwise
• How to calculate the result of two or more moments applied to an object
• That in equilibrium clockwise moments = anticlockwise moments
• Some applications of moments such as levers and cranes