Topic 3 - Motion and Forces Flashcards
What is meant by the term ‘speed’?
How fast you’re going with no regard to the direction.
What is meant by the term ‘velocity’?
Velocity is how fast you’re going but must also have a direction.
What is meant by the term ‘displacement’?
The distance in a particular direction.
What makes something a vector quantity?
A measurement that has magnitude (size) and direction.
What is the formula for speed?
Speed=distance/time
What is meant by the term ‘acceleration’?
A measure of how quickly velocity is changing. This can be a change in speed or a change in direction or both. (Only calculate change in speed).
What is the formula for acceleration?
Acceleration=change in velocity/time taken
What is the symbol equation for acceleration?
(v-u)/t
What does the letter u represent?
The initial velocity.
What does the letter v represent?
The final velocity.
What is the unit for acceleration?
m/s2(squared)
What are speed and velocity measured in?
m/s or km/h or mph
On a distance-time graph, what are the x and y axis labels?
x is time
y is distance
On a distance-time graph, what does the gradient represent?
Speed
On a distance time-graph, when the line is flat, what does this represent?
Not moving, stopped
On a distance-time graph, what does it meant when it is going downwards?
It is going back towards the start point
On a distance-time graph, what do curves represent?
Acceleration or deceleration
Steepening curve means speeding up, levelling off curve means slowing down.
How do you calculate speed from a distance time graph?
vertical/horizontal (bearing in mind the scales)
What are the labels for the x and y axis on a velocity-time graph?
x is time
y is velocity
On a velocity-time graph, what does the gradient represent?
The acceleration
On a velocity-time graph, what do the flat sections represent?
Steady speed
Steeper the graph, the greater the acceleration
On a velocity-time graph, what do the uphill sections show?
Acceleration
On a velocity-time graph, what do the downhill sections represent?
Deceleration
Using a distance-time graph, how do you work out the distance travelled in a certain amount of time?
Work out the area underneath that time section
On a velocity-time graph, what does a curve mean?
Changing acceleration
How do you work out the acceleration using a velocity-time graph?
Gradient therefore vertical/horizontal
When force arrows are drawn, what do the lengthen and direction represent?
Length it the size of the force and direction shows the direction of the force
What does it mean if the arrows come in opposite pairs and they the same size?
The forces are balanced
Describe the forces on a stationary object
Forces are balanced. Weight (gravity) is acting downwards with an equal reaction force going upwards of reaction. There must also be equal, or no horizontal forces.
What happens to an object if one force doesn’t have a reaction force?
It accelerates
Describe the forces when an object is moving horizontally or vertically at a steady speed.
All forces are equal
Describe the forces when an object is accelerating
You have a resultant force, shown by one arrow being longer than the other. The bigger the unbalanced force, the greater the acceleration.
What is meant by the term ‘weight’ and what it is measured in?
Weight is caused by the pull of gravity and is measured in Newtons.
What is meant by the term ‘mass’ and what is it measured in?
Mass is not a force. Mass is measured in kg and is how much ‘stuff’ is in an object.
What is the equation to work out weight?
Weight=massxgravitational field strength (W=mxg)
Describe what happens to accelerating objects in space
Gravity makes all objects accelerate at the same rate, no matter on their size. This is because there’s no air resistance in space, so there is only the force of gravity. Larger objects don’t have a larger air resistance like on earth and therefore accelerate at the same speed as smaller objects
Describe how objects falling reach terminal velocity when falling through somewhere with air resistance.
At first, objects falling have more force (weight) accelerating than resistance slowing them down. As the speed increases, the air resistance increases too, gradually reducing air resistance until weight it equal to air resistance. When these forces are balanced, the object won’t accelerate any more, as it has reached it’s maximum speed or terminal velocity.
What is the rule for when you exit force on an object?
If object A exerts a force on object B then object B exerts the exact opposite force on object A. (At the exact moment the two objects touch)
What happens if there is no resultant force?
If there is zero resultant force acting on a body (the forces are balanced) then the body will remain at rest, or else if it’s already moving it will just carry on at the same velocity.
How does a resultant force affect an object?
If the resultant force acting on a body is not zero, it will accelerate in the direction of the resultant force.
What are the five from acceleration can be in?
Starting, stopping, speeding up, slowing down, changing direction
What is the equation for force?
Force=mass x acceleration
