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65 Cards in this Set
- Front
- Back
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what is the same about speed and velocity?
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they are both measures of how fast something is going (m/s)
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what is different about speed and velocity?
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speed is just about how fast something is going, but velocity must also include the direction
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what is the distance in a particular direction called?
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displacement
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what is acceleration?
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how quickly the velocity is changing
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what can the change in velocity be?
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direction and/or speed
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what is a vector quantity?
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something with a magnitude and direction
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give 3 examples of a vector quantity
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velocity
displacement acceleration |
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what are two types of graphs we need to understand?
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D-T and V-T graphs
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what is a D-T graph?
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a distance-time graph
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what does the gradient represent?
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speed
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what do the flat sections represent?
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where it has stopped
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the steeper the graph...
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...the faster it is going
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what do negative gradients show?
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it is going back to the starting point (direction has changed)
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what does a steepening curve represent?
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it is speeding up (accelerating)
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what does a levelling curve represent?
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it is slowing down (decelerating)
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how do you work out the speed?
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rise divided by run
--->gradient = speed |
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What is a V-T graph?
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a velocity-time graph
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what does the gradient represent?
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acceleration
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what do the flat sections represent?
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a steady speed (not accelerating)
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the steeper the gradient...
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...the greater the acceleration/deceleration
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a negative gradient represents...
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....deceleration
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how would you work out the distance travelled in a time interval?
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work out the area below the graph within that time interval
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what does a curve represent?
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a changing acceleration e.g. they are getting faster more quickly/in less time
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how do you work out the acceleration?
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rise divided by run
--->gradient = acceleration |
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what are the forces like on a stationary object?
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they are all equal/balanced
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what is the force acting downwards on the object?
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gravity/weight
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what is the force acting upwards on the object?
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the reaction force from the surface supporting the object
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what would happen if there was no reaction force?
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the object would accelerate downwards due to the unequal force of gravity
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describe how horizontal forces can impact on the movement of the object
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the have to be equal or zero and in opposite directions for the object to remain stationary.
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how are equal forces shown on diagrams
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with the same length/sized arrows
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describe the forces acting on a steady horizontal velocity of a car
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the weight and reaction forces are equal and so are the thrust and drag of the car
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describe the forces acting on a steady vertical velocity of a skydiver
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the drag and the weight are equal
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describe the forces acting on a horizontal accelerating velocity of a car
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the weight and reaction force are equal but the thrust is greater than the drag
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how would this be shown on a diagram?
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the upwards and downwards arrows would be of equal lengths and in opposite directions but the thrust would be a longer arrow than the drag which point in opposing directions
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describe the forces acting on a vertical accelerating velocity of a skydiver
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there is less force acting upwards (drag) than the weight which acts downwards
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what is the difference between mass and weight?
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weight is a force (Newtons, N)
mass is just how much matter there is in something (kilograms, Kg) |
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what is weight caused by?
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the pull of gravity
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which changes depending on whether you are on the moon or one earth: the mass or the weight?
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the weight
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what is the gravitational field strength on earth?
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about 10 N/Kg
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what is the gravitational field strength on the moon?
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about 1.6 N/Kg
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what is the accelerating force that acts on all objects?
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gravity
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what happens in a vacuum?
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all object accelerate at the same rate
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why?
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because there is no air resistance
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describe the forces acting on an object when it first starts falling
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it has weight/gravity acting downwards but not much drag so it accelerates because the forces are unequal
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what happens as the object accelerates?
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it speeds up and thereby increases the resistance/drag acting upon it
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what happens to the acceleration as a result?
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the acceleration reduces
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what happens as the acceleration reduces?
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eventually, the air resistance becomes equal to the weight
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what occurs when the drag and weight become equal?
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the object reaches a steady speed and won't accelerate - the object has reached its terminal velocity
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what is terminal velocity?
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the maximum speed it will go
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what happens is an object (A) exerts a force of another object (B)
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Object B exerts the exact opposite force object A
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for example, if you push a shopping trolley....
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....it pushes back on you just as hard
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and if you stop pushing...
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....the trolley stops pushing you back
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what is the force the Object A exerts called?
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the action force
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what is the resulting forcing that Object B exerts called?
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the reaction force
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what is a resultant force?
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the overall force acting on a object
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what is a zero resultant force?
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when all the forces are balanced
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what happens if there is a zero resultant force acting upon an object?
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the object will remain at the same velocity (or zero velocity if at rest)
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what must the forces be like on a bus that is moving at a constant velocity?
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they must all be equal - zero resultant force
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if the resultant force acting on a body is not zero...
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...it will accelerate in the direction of the resultant force
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an unbalanced force will always produce..
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...acceleration or deceleration
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what are the five situations that acceleration/deceleration takes place?
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1. starting
2.stopping 3.speeding up 4.slowing down 5.changing direction |
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true or false:
if something is moving there must be an overall resultant force acting on it |
FALSE - if there is an Overall force, it must be Accelerating/Decelerating
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the bigger the resultant force....
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....the greater the acceleration/deceleration
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if the mass of an object is greater, will it have a bigger or small acceleration?
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smaller
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what would have to be done to get a larger mass to accelerate as fast as a smaller mass?
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give it a greater resultant force
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