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33 Cards in this Set
- Front
- Back
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What is the displacement of an object? |
It's net distance from its starting point together with an indication of direction |
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What does a steeper gradient of a distance time graph show? |
A higher speed |
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In many everyday situations, what is acceleration used to mean? |
The change in speed of an object in a given time interval |
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What is the instantaneous velocity of an object? |
It's instantaneous speed together with an indication of the direction |
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What is the velocity of an object moving in a straight line? |
Positive if it is moving in one direction Negative if it is moving in the opposite direction |
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What does a force arise from? |
An interaction between two objects |
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What happens when two objects interact? |
Both always experience a force and that these two forces for an interaction pair |
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What are the properties of two forces in an interaction pair? |
Equal in size Opposite in direction They act on different objects |
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What is the interaction between two surfaces which slide relative to each other? |
Each surface experiences a force in the direction that prevents relative movement This is called friction |
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What is the interaction between an object and a horizontal surface it is resting on? |
The object pushes down on the surface, the surface pushes up on the object with an equal force and this is called the reaction of the surface |
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How do friction and reaction of the surface arise? |
In response to the action of an applied force and their size matches the applied force up to a limit |
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What is the resultant force on an object? |
The sum of all the individual forces acting on it, taking their directions into account |
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What happens if a resultant force acts on an object? |
It causes a change in momentum in the direction of force |
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What is momentum(kgm/s) equal to? |
Mass (kg) × velocity (m/s) |
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What is the size of the change of momentum proportional to? |
The size of the resultant force acting on the object and to the time for which it acts: Change of momentum=resultant force×time for which itacts (Kgm/s) (N) (s) |
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In what terms can horizontal motion of objects(cars or bikes? be analysed? |
A driving force (by engine or the cyclist) And a counter force (due to friction and air resistance) |
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What happens for an object moving in a straight line if the driving force is greater than the counter force? |
The vehicle will speed up |
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What happens for an object moving in a straight line if the driving force is equal to the counter force? |
The vehicle will move at at constant speed in a straight line |
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What happens for an object moving in a straight line if the driving force is smaller than the counter force? |
The vehicle will slow down |
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What happens in situation involving a change in momentum? |
The longer the duration of the impact, the smaller the average force for a given change in momentum |
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In what terms of vertical motion of objects(falling or thrown up) be analysed? |
In terms of the forces acting (gravity or air resistance) |
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What happens to the momentum if the resultant force of an object is zero? |
It's momentum does not change it stays stationary If it is already moving it continues at a constant velocity |
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What is the energy of a moving object called? |
Kinetic energy |
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What happens when an object is raised and then when it falls? |
When raised its gravitation potential energy increases As it falls the gravitational potential energy decreases |
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What happens when a force moves an object? |
It does work |
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What happens when work is done on an object? |
Energy is transferred to the object |
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What happens when work is done by an object? |
Energy is transferred from the object to something else |
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What happens when an object is lifted to a higher position above the ground? |
Work is done by a lifting force This increases the gravitational potential energy |
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What happens when force acting on an object makes its velocity increase? |
The force does work on the object and results in an increase in its kinetic energy |
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What is the link between mass of an object, it's speed and it's kinetic energy? |
The greater the mass of an object and the faster it is moving, the greater the kinetic energy |
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When is energy conserved? |
It is always conserved in any event or process |
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What happens when the friction and air resistance can be ignored? |
An objects kinetic energy changes by an amount equal to the work done on it by an applied force |
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What will air resistance or friction cause? |
The gain in an object's kinetic energy to be less than the work done on it by an applied force in the direction of motion because some energy is dissappear through heating |
