Forces

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Sample objectives

What this unit covers

• Forces and their interactions: Define a vector quantity as a quantity with magnitude and direction.
• Forces and their interactions: Identify displacement, velocity, acceleration, force, weight and momentum as vector quantities in GCSE contexts.
• Forces and their interactions: State that balanced forces have a resultant force of zero.
• Forces and their interactions: Interpret simple free-body diagrams showing forces on one object.
• Forces and their interactions: Label force arrows with the type of force and direction.
• Forces and their interactions: Identify gravitational, electrostatic and magnetic forces as non-contact forces.
• Forces and their interactions: Calculate mass from weight and gravitational field strength.
• Forces and their interactions: Define weight as the force acting on an object due to gravity.
• Work done and energy transfer: Calculate work done from force and distance.
• Work done and energy transfer: Calculate distance from work done and force.
• Work done and energy transfer: Describe how braking forces transfer energy from a vehicle's kinetic energy store.
• Work done and energy transfer: Distinguish thinking distance from braking distance in stopping-distance contexts.
• Forces and elasticity: Identify the limit of proportionality on a force-extension graph.
• Forces and elasticity: Describe extension as the increase in length of an object when stretched.
• Forces and elasticity: Calculate force from spring constant and extension.
• Forces and elasticity: Convert extension between centimetres and metres where required.
• Forces and elasticity: Describe how to measure the original length of a spring before adding loads.
• Forces and elasticity: Explain why the spring should not be overloaded beyond its elastic limit.
• Forces and elasticity: Use the equation elastic potential energy = 0.5 x spring constant x extension squared.
• Forces and elasticity: Interpret force-extension graphs in terms of energy stored where appropriate.
• Moments, levers and gears (physics only): (Physics only) Calculate force from moment and perpendicular distance.
• Moments, levers and gears (physics only): (Physics only) Explain that increasing perpendicular distance increases the moment for a fixed force.
• Moments, levers and gears (physics only): (Physics only) Explain how a lever can increase the moment produced by a force.
• Moments, levers and gears (physics only): (Physics only) Identify input gear and output gear in simple gear diagrams.
• Pressure and pressure differences in fluids (physics only): (Physics only) Calculate force from pressure and area.
• Pressure and pressure differences in fluids (physics only): (Physics only) Apply pressure ideas to everyday examples such as sharp blades, snowshoes or high heels.
• Pressure and pressure differences in fluids (physics only): (Physics only) Explain that pressure in a liquid is caused by the weight of liquid above.
• Pressure and pressure differences in fluids (physics only): (Physics only) Use the equation pressure = height of column x density x gravitational field strength.
• Pressure and pressure differences in fluids (physics only): (Physics only) Link atmospheric pressure to the weight of air above a surface.
• Pressure and pressure differences in fluids (physics only): (Physics only) Describe atmospheric pressure as pressure caused by air particles colliding with surfaces.
• Forces and motion: Use the equation distance travelled = speed x time.
• Forces and motion: Distinguish average speed from instantaneous speed.
• Forces and motion: Identify units on distance and time axes.
• Forces and motion: Describe motion from a distance-time graph in words.
• Forces and motion: Calculate acceleration from change in velocity and time.
• Forces and motion: Define acceleration as the rate of change of velocity.
• Forces and motion: Calculate distance travelled from the area under a velocity-time graph.
• Forces and motion: Distinguish distance-time graphs from velocity-time graphs.
• Forces and motion: (HT only) Use consistent units for velocity, acceleration and distance.
• Forces and motion: (HT only) Square and square-root velocity values correctly in calculations.
• Forces and motion: State Newton's first law in terms of motion remaining unchanged when resultant force is zero.
• Forces and motion: Explain that a non-zero resultant force causes acceleration.
• Forces and motion: Describe how to investigate the effect of changing mass on the acceleration of a trolley.
• Forces and motion: Explain why repeated measurements improve reliability.
• Forces and motion: Define thinking distance as the distance travelled during the driver's reaction time.
• Forces and motion: Explain how poor road conditions can increase braking distance.
• Momentum: (HT only) Distinguish momentum from kinetic energy in collision explanations.
• Momentum: (HT only) Apply MS 3b and MS 3c skills when rearranging p = mv.
• Momentum: (HT only) Apply qualitative momentum reasoning to vehicle safety scenarios.
• Momentum: (HT only) Describe how increasing impact time reduces the force for the same change in momentum.