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22 Cards in this Set
- Front
- Back
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What does the gradient of a distance-time graph tell you? |
SPEED Flat sections- Stationary Curves- acceleration/deceleration Steeper the gradient- faster it's going Downhill sections- coming back to starting point
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What does the gradient of a velocity-time graph tell you? |
ACCELERATION Flat sections- Constant speed Curves- changing acceleration Steeper the gradient- greater acceleration/ deceleration Downhill sections- deceleration Negative velocity- opposite direction |
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What's the difference between speed and velocity? |
Speed- how fast something is going in a given amount of time Velocity- Speed and direction Instantaneous velocity- speed and direction at a given moment in time Negative velocity- travelling in the opposite direction |
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What is acceleration? |
Change in velocity/speed in a certain amount of time deceleration- slowing down in a certain amount of time |
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When do forces occur? |
-Forces occur when two objects interact e.g- when you push the wall the wall will push back using equal forces in the opposite direction
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What are interaction pairs? |
-When an object exerts a force and it experiences a force in return this is called an interaction pair Equal in size Opposite direction You only have an interaction pair if the forces are caused by the interaction. |
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What happens when one force causes another? |
This is called a reaction force This is not the same as interaction pairs e.g- when a book is placed on a table the book pushes down with a force equal to its weight- the table exerts a force upwards on the book-reaction force- tables response |
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What do moving objects normally experience? |
Friction- when an object is moving relative to another one, both objects experience a force in the direction that opposes the movement Friction is a reaction force
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What are the 3 types of friction? |
Friction between solid surfaces which are gripping- e.g.-walking Friction between solid surfaces which are sliding past each other-e.g.-car engine parts Resistance/Drag from fluids- (liquids,gases,air)-e.g.-cars |
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What do arrows show in terms of forces? |
Length of arrow- size of force Direction of arrow- direction of force If arrows are opposite pairs-same size-forces are balanced |
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What causes balanced forces? |
The reaction of a surface- if an objects resting on a surface it pushes downwards because of its weight this causes an equal reaction force pushing upwards on the object Steady speed- object is moving at a steady speed the forces must be in balance if an object changes speed the forces are not equal
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What is resultant force? |
-the overall force acting on an object- when you add up all the individual forces and directions -decides the motion of an object-accelerate, decelerate, steady speed -If there is an resultant force acting on an object its speed or direction or both changes |
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What causes unbalanced forces? |
If a car exerts a bigger driving force than drag counter force then the car will accelerate and forces will be unbalanced
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What is momentum? |
How hard it would be to stop an object moving Greater the mass or velocity of an object, the more momentum it will have
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What does the change in momentum depend on? |
the force when a resultant force acts on an object it causes a change in momentum in the direction of the force the change of momentum it causes is proportional to the size of the force and the time it acts for the bigger the force and the longer it acts for the bigger the change in momentum |
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What do car safety features do? |
Car safety features reduce forces this is because if a car had a collision the safety features would increase the collision time and therefore reduce the forces on passengers |
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What car safety features are there? |
Crumple zones- crumple on impact, increasing the time taken for the car to stop Air bags- slow you down more gradually Seat belts- stretch slightly increasing the time taken for the wearer to stop and reduces forces on chest Cycle and motorcycle helmets- provide padding the increases time taken for your head to stop |
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What is ''work done''? |
Energy transferred when a force moves an object it does work and energy is transferred to the object -when something moves something else is providing energy to move it -the thing putting in the effort needs an energy supply -it moves the object by transferring the energy it has -energy can be transferred usefully or it can be wasted (heat) Amount of energy transferred (J) = Work done (J) |
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What is Kinetic energy? |
Energy of movement the kinetic energy of something depends on its mass and speed the greater the mass = bigger kinetic energy to increase kinetic energy you need to increase velocity- apply force- do work if you work on an object but it doesn't accelerate it hasn't increased in kinetic energy |
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How is work done and kinetic energy linked? |
If work is done then energy is transferred which increases the amount of kinetic energy however energy is always conserved (can't create or destroy it)- it gets transformed energy gets wasted as heat because of friction or air resistance if there's no friction or air resistance, kinetic energy = work done The increase in an objects K.E is normally a bit less than the amount of work done on it, because some energy is wasted as heat
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What is gravitational potential energy? |
Height Energy energy stored in an object when you raise it to a height against force of gravity lift object = increase in GPE as its lifted object falls = GPE decreases as it falls increase GPE by doing work increase in GPE = work done by lifting force |
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How are Kinetic energy and Gravitational potential energy linked? |
When something falls its GPE is converted into KE Most is converted but some is wasted as heat due to air resistance K.E gained = GPE lost |
