What is the formula to find speed? - speed = distance ÷ time, What does the slope/gradient of a distance time graph show? - speed, What does a flat section on a distance time graph show? - no movement or stopped, What is the difference between speed and velocity? - speed is just a number velocity has direction too, What is the speed of a car that travels 1500m in 7.5s? - 200m/s, What does the slope/gradient of a velocity time graph show? - acceleration, What does a flat section on a velocity time graph show? - steady speed, What type of graph is a tacograph used in lorries and buses? - velocity time graph, True or false you never have just one force? - True forces always come in opposite pairs, The downward force we feel pulling us down is called? - Weight due to gravity, When we sit on a chair we feel a force pushing back against us. What is it called? - Reaction or reactive force, If forces are equal and opposite we say they are? - Balanced, If forces are unbalanced what happens? - A resultant force will act and cause a change in the direction of that resultant force, The unit we measure force in is called? - Newton (N), The name of the force that stops objects moving or slows them down? - Friction (also known as drag), How do we show the size and direction of forces on diagrams? - Arrows, How would you draw arrows to show balanced forces? - Arrows equal length but opposite direction to each other, A car experiences a much greater thrust force than a drag force what happens? - It will accelerate in the direction of the thrust force because the forces are unbalanced, The bigger the resultant force on a car means what? - The bigger the acceleration (or deceleration), If the resultant force is zero what does this mean? - No change, What is momentum? - A measure of how hard it is to stop an object moving., What is the formula for momentum - Momentum = mass x velocity, A kangaroo of mass 65kg is hopping at 10 m/s what is it's momentum? - 65kg x 10m/s = a momentum of 650kg m/s, Which has more momentum (if travelling at the same speed) a car or a train? - The train because it has the bigger mass., What happens when a resultant force acts on an object? - It causes a change in momentum, What two things cause a change in momentum? - Size of the force and the amount of time the force acts on the object, What is the formula for change in momentum? - Change in momentum = force x time force acts, A comet has momentum of 15kg m/s it is pushed with force of 2500 N for 0.7s. What is change in momentum? - 2500N x 0.7s = 1750 kg m/s (take away original momentum 15kg m/s) so change momentum is 1735kg m/s, If momentum changes quickly (e.g. two cars collide) What does that mean for the driver? - The forces on the driver (and car) will be very large and likely to cause injury, What safety features in cars slow down the rate of change of momentum (and reduce the forces on the driver?) - Crumple zones, What is the definition of Work? - When a force acts on an object, Change in energy = ? - Change in energy = work done, What is the formula for work done? - Work done (J) = force (N) x distance (m), How much work is done when kids drag an old tractor tyre with a force of 340 N for a distance of 5m to their bonfire? - Work done (J) = force (N) x distance (m) so 340N x 5m = 1700J of work, Kinetic energy is energy of ? - Kinetic energy is energy of movement, The formula for kinetic energy is? - Kinetic energy = 1/2 x mass x velocity2, If an object is travelling faster does it have more or less kinetic energy? - The faster an object moves the bigger its kinetic energy, If an object is heavier (more mass) does it have more or less kinetic energy? - If an object is heavier (more mass) does it has more kinetic energy?, What are the units we measure kinetic energy in? - Kinetic enrgy is measured in joules, What is the definition of G.P.E. ( gravitational potential energy) ? - Also known as height energy. It is the energy an object has stored in it when you lift it up against the force of gravity., What is the formula for GPE? - GPE = weight (N) x change in height (m), What is the GPE of a cow weighing 4000N which jumps 10m up into a tree? - GPE = weight (N) x change in height (m) so 4000N x 10m = 40, What is the rule about kinetic energy and GPE on falling objects (e.g. a roller coaster) - As the roller coaster falls down the track; kinetic energy gained = GPE lost (and vice versa),

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