P3 Spaced learning Forces for transport

Speed Speed = Average Distance/Time KM x 1000 = M M / 1000 = KM Average Speed Cameras Takes two photos, a certain time apart, when the vehicle moves over marked lines a know distance apart. Graphs – distance / time graphs, how the distance changes over time. Gradient (steepness) = speed (steeper faster) Steady speed – straight diagonal line (up or down) Stationary – horizontal line increasing the speed, increases the distance travelled in the same time increasing the speed, reduces the time to cover the same distance. distance = average speed × time =(u + v)/2 × t d is the distance u is the starting speed v is the finishing speed t is the time taken You need to be able to draw one. Non – uniform speed: Curved line upwards – acceleration Curved line downwards - decceleration Use the unit s on the graph combined for speed

Changing speed acceleration = change in speed / time taken A change in speed per unit of time - metres per second squared (m/s 2 ) - involves change in speed and/or direction Velocity – speed and direction You need to be able to draw one Change in speed = end speed – start speed Horizontal line - constant speed Straight line (positive gradient) - constant positive acceleration (speeding up) Straight line (negative gradient) - constant negative acceleration e.g. -2m/s (slowing down) or deceleration Steeper line (greater change in speed in given time)– higher acceleration Curved line –up increasing acceleration –down decreasing acceleration Calculate distance – area under the graph (meters) Objects moving in opposite directions at the same speed, velocities have identical magnitude but opposite signs. E.g. +30m/s and – 30m/s Relative velocity: Velocity A – Velocity B e.g. +30 m/s m/s =+10 m/s OR +30 m/s m/s =+50 m/s Gradient = acceleration

Forces and motion force = mass × acceleration Thinking distance - the distance travelled between the need for braking occurring and the brakes starting to act. Increased if: Tired, Distracted or not concentrating, Under the influence of alcohol or other drugs, increased speed, distractions or lack of concentration. Braking distance - the distance taken to stop once the brakes have been applied. Increased if: The car's brakes or tyres are in poor condition, The road and weather conditions are poor (icy or wet roads, for example)., increased speed, Friction, mass, speed, braking force. Stopping distance - thinking distance + braking distance. Road safety - Speed limits - go no faster than safe for normal conditions. Road conditions- icy etc. ‘tail gates’ –drives too close to the vehicle in front, (inside thinking distance). Force - newtons, N Mass - kilograms, kg Acceleration -metres per second squared, m/s 2 Resultant force is zero - stay at the same speed. Resultant force is not zero - speed up or slow down, +ve or –ve. Speed up - resultant force is in the same direction as object is moving Slow down - resultant force is in the opposite direction stopping distance = thinking distance + braking distance Speed and: thinking distance – increases linearly braking distance – increases as a squared relationship e.g. x2 x4, x3 x9.

Work and Power weight = mass × gravitational field strength Weight -newtons, N Mass -kilograms, kg The gravitational field strength -newtons per kilogram, N/kg Mass - how much stuff is in an object. Weight - force acting on that stuff due to gravity. gravitational field strength of the Moon is about one-sixth of that of the Earth Work done = force × distance Work done -joules, J Force - newtons, N Distance - metres, m J also used for energy Examples lifting weights climbing stairs pulling a sledge pushing a shopping trolley. Depends on: the size of the force in newtons (N) the distance travelled in metres (m). Power = Work done / time How quickly work is being done. Watts (W). Cars: have different power ratings have different engine sizes Affecting fuel consumption – environmental issues, cost Use and understand the derivation of the power equation in the form: power = force × speed Power -watts, W Work done -joules, J Time -seconds, s

Energy on the move Kinetic energy – depends on mass and speed KE = ½ mv2 or KE = ½ × m × v2 KE = the kinetic energy in joules, J m = the mass in kilograms, kg v = the speed in metres per second, m/s (derivatives of) fossil fuels - fuels in road transport: petrol, diesel. Will run out kinetic energy proportional to speed squared, braking distances proportional to the speed squared. Rearrange equation for kinetic energy. m = (2 × KE) ÷ v 2 v 2 = (2 × KE) ÷ m Alternatives - bio-fuels and solar energy. reduce pollution at the point of use produce pollution in their production may lead to an overall reduction in CO2 emissions. Electricity used for road transport, battery driven cars, solar power/cars with solar panels, do not pollute at point of use. Affect on fuel consumption: Shape - wedge shape of sports car, deflectors on lorries and caravans, roof boxes on cars, driving with car windows open. Other factors - Driven uphill a lot, Carrying large loads or not, Driven at high speed, Driven over rough road surfaces, Driven with underinflated tyres. energy required to increase KE, energy required to do work against friction, driving styles and speeds, road conditions. Carbon dioxide - greenhouse gas (global warming) Sulfur dioxide - cause of acid rain. Recognise that battery driven cars need to have the battery recharged: this uses electricity from a power station cause pollution

Crumple zones Momentum = mass × velocity Momentum - kilograms metres per second, kg m/s Mass - kilograms, kg Velocity - metres per second, m/s Sudden change in momentum – large force- cause injury Force = change in momentum ÷ time Force - newtons, N Change in momentum - kilograms metres per second, kg m/s Time - seconds, s : Change in momentum - the longer the time taken, the smaller the force needed. Car safety features Risks and benifits

Falling safely

The energy of games and theme rides

Musical Chairs

Speed Speed = Average Distance/Time KM x 1000 = M M / 1000 = KM Average Speed Cameras Takes two photos, a certain time apart, when the vehicle moves over marked lines a know distance apart. Graphs – distance / time graphs, how the distance changes over time. Gradient (steepness) = speed (steeper faster) Steady speed – straight diagonal line (up or down) Stationary – horizontal line increasing the speed, increases the distance travelled in the same time increasing the speed, reduces the time to cover the same distance. distance = average speed × time =(u + v)/2 × t d is the distance u is the starting speed v is the finishing speed t is the time taken You need to be able to draw one. Non – uniform speed: Curved line upwards – acceleration Curved line downwards - decceleration Use the unit s on the graph combined for speed

Changing speed acceleration = change in speed / time taken A change in speed per unit of time - metres per second squared (m/s 2 ) - involves change in speed and/or direction Velocity – speed and direction You need to be able to draw one Change in speed = end speed – start speed Horizontal line - constant speed Straight line (positive gradient) - constant positive acceleration (speeding up) Straight line (negative gradient) - constant negative acceleration e.g. -2m/s (slowing down) or deceleration Steeper line (greater change in speed in given time)– higher acceleration Curved line –up increasing acceleration –down decreasing acceleration Calculate distance – area under the graph (meters) Objects moving in opposite directions at the same speed, velocities have identical magnitude but opposite signs. E.g. +30m/s and – 30m/s Relative velocity: Velocity A – Velocity B e.g. +30 m/s m/s =+10 m/s OR +30 m/s m/s =+50 m/s Gradient = acceleration

Forces and motion force = mass × acceleration Thinking distance - the distance travelled between the need for braking occurring and the brakes starting to act. Increased if: Tired, Distracted or not concentrating, Under the influence of alcohol or other drugs, increased speed, distractions or lack of concentration. Braking distance - the distance taken to stop once the brakes have been applied. Increased if: The car's brakes or tyres are in poor condition, The road and weather conditions are poor (icy or wet roads, for example)., increased speed, Friction, mass, speed, braking force. Stopping distance - thinking distance + braking distance. Road safety - Speed limits - go no faster than safe for normal conditions. Road conditions- icy etc. ‘tail gates’ –drives too close to the vehicle in front, (inside thinking distance). Force - newtons, N Mass - kilograms, kg Acceleration -metres per second squared, m/s 2 Resultant force is zero - stay at the same speed. Resultant force is not zero - speed up or slow down, +ve or –ve. Speed up - resultant force is in the same direction as object is moving Slow down - resultant force is in the opposite direction stopping distance = thinking distance + braking distance Speed and: thinking distance – increases linearly braking distance – increases as a squared relationship e.g. x2 x4, x3 x9.

Work and Power weight = mass × gravitational field strength Weight -newtons, N Mass -kilograms, kg The gravitational field strength -newtons per kilogram, N/kg Mass - how much stuff is in an object. Weight - force acting on that stuff due to gravity. gravitational field strength of the Moon is about one-sixth of that of the Earth Work done = force × distance Work done -joules, J Force - newtons, N Distance - metres, m J also used for energy Examples lifting weights climbing stairs pulling a sledge pushing a shopping trolley. Depends on: the size of the force in newtons (N) the distance travelled in metres (m). Power = Work done / time How quickly work is being done. Watts (W). Cars: have different power ratings have different engine sizes Affecting fuel consumption – environmental issues, cost Use and understand the derivation of the power equation in the form: power = force × speed Power -watts, W Work done -joules, J Time -seconds, s

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