Motion - Equations and Graphs Flashcards
Describe what is meant by a ‘scalar’.
A quantity which consists of a magnitude (size) only.
Describe what is meant by a ‘vector’.
A quantity which consists of a magnitude (size) and direction.
Give two examples of scalar quantities.
Distance/speed/mass/time/energy
Give two examples of vector quantities.
Displacement/velocity/acceleration/force/weight/momentum etc
Describe what is meant by ‘distance’.
How far an object has travelled from the starting point to the finishing point of a journey, regardless of its direction. It is a scalar quantity.
Describe what is meant by ‘displacement’.
The shortest distance between the starting point and finishing point of a journey, which takes into account the direction of travel. It is a vector quantity.
Explain the difference between distance and displacement.
Distance is how far an object has travelled from the starting point to the finishing point of a journey, regardless of its direction. Displacement is the shortest distance between the starting point and finishing point of a journey, which takes into account the direction of travel. Distance is a scalar and displacement is a vector.
Define the term ‘speed’.
The distance travelled per unit time. It is a scalar quantity.
Describe what is meant by ‘average speed’.
The total distance travelled by an object measured over the total time taken.
Write down the equation relating distance, average speed and time.
d=vt
State the symbol and units for distance.
d, m
State the symbol and units for average speed.
v bar, m/s
State the symbol and units for time.
t, s
Define the term ‘velocity’.
The displacement per unit time. It is a vector quantity.
Write down the equation relating displacement, average velocity and time.
s=vt
State the symbol and units for displacement.
s, m
State the symbol and units for average velocity.
v bar, m/s
State the rule used when adding two vectors together.
The two vectors must be joined nose to tail.
When adding two vectors together, the final vector drawn from the start to the finish point is called the ______________ vector.
Resultant
State the sign convention normally used for objects moving horizontally.
right = +ve, left = -ve
State the sign convention normally used for objects moving vertically.
up = +ve, down = -ve
Sketch the velocity-time graph for an object at rest. No numerical values are required on the axes.
Axes with no line.
Sketch the velocity-time graph for an object moving with constant velocity. No numerical values are required on the axes.
Axes with a straight line of gradient 0.
Sketch the velocity-time graph for an object moving with uniform acceleration. No numerical values are required on the axes.
Axes with a straight line of positive gradient.
Sketch the velocity-time graph for an object moving with uniform deceleration. No numerical values are required on the axes.
Axes with a straight line of a negative gradient.
Sketch the velocity-time graph for an object that changes direction. No numerical values are required on the axes.
Axes with a line that crosses the x-axis.
How is a change in direction shown on a velocity-time graph?
By moving above or below the x-axis.
Describe how to find displacement from a velocity-time graph.
s = area under v-t graph
When finding displacement from a velocity-time graph, which two shapes can we often split the graph into to calculate the total area?
Rectangles, triangles
Write down the equation used to calculate the area of a rectangle.
a= l x b
Write down the equation used to calculate the area of a triangle.
a= 1/2 l x b
Describe how to find acceleration from a velocity-time graph.
a = gradient of line on a v-t graph OR use acceleration equation
Write down the equation used to calculate the gradient of a straight line.
y2-y1/x2-x1
Describe how you would obtain an acceleration-time graph from a velocity-time graph.
Calculate the gradient of the lines on the v-t graph.
Describe how you would obtain a displacement-time graph from a velocity-time graph.
Calculate the area under the v-t graph.
Sketch the displacement-time, velocity-time and acceleration-time graphs for an object moving with constant velocity. No numerical values are required on the axes.
Displacement-time - axes with a straight line of a positive gradient.
Velocity-time - axes with a straight line of gradient 0.
Acceleration-time - axes with no line.
Sketch the displacement-time, velocity-time and acceleration-time graphs for an object moving with uniform acceleration. No numerical values are required on the axes.
Displacement-time - line gradually steepens as velocity increases.
Velocity-time - axes with a straight line of a positive gradient
Acceleration-time - axes with a straight line of gradient 1
Sketch the displacement-time, velocity-time and acceleration-time graphs for an object moving with uniform deceleration. No numerical values are required on the axes.
Displacement-time - line gradually flattens out as velocity decreases.
Velocity-time - axes with a straight line of a negative gradient.
Acceleration-time - axes with a straight line of gradient 1, below the x-axis.
Sketch the velocity-time graph for an object thrown vertically upwards. No numerical values are required on the axes.
Axes with a straight line of negative gradient that starts above x-axis and crosses it which shows peak of height.
Sketch the acceleration-time graph for an object thrown vertically upwards. No numerical values are required on the axes.
Axes with a straight line of gradient 1 that begins above the x-axis but then is drawn below it to indicate the peak of height.
For an object thrown vertically upwards, state the speed of the object at its highest point in motion.
0 m/s
Sketch the velocity-time graph for a bouncing ball. No numerical values are required on the axes.
Axes with straight lines of negative gradients which interchange between being above and below the x-axis to indicate changes in direction.
Write down the first equation of motion relating initial velocity, final velocity, acceleration and time.
a=(v-u)/t
Write down the second equation of motion relating displacement, initial velocity, acceleration and time.
s=ut+1/2at^2
Write down the third equation of motion relating displacement, initial velocity, final velocity and acceleration.
v^2=u^2+2as
Write down the fourth equation of motion relating displacment, initial velocity, final velocity and time.
s=1/2(u+v)t
State the symbol and units for initial velocity.
u, m/s
State the symbol and units for final velocity.
v, m/s
To help you answer a question involving equations of motion, what should you always write down at the start?
suvat
Define the term ‘acceleration’.
The change in velocity per unit time. It is a vector quantity and is given by the gradient of the line on a velocity-time graph.
State the symbol and units for acceleration.
a, ms-2
What does a negative acceleration represent?
A deceleration
Describe an experiment to measure the acceleration of an object down a slope. Your answer should include the measurements taken and equipment used.
Use a trolley with double mask and one light gate. Let the trolley roll down a ramp. Measure the length of each mask using a ruler. The timer measures the time for each card to cut the light gate, as well as the overall time to pass, giving initial and final velocities for the trolley and the total time. Use a = v-u/t to calculate acceleration.
Describe an experiment to measure the acceleration of a falling object. Your answer should include the measurements taken and equipment used.
Measure the time taken (using a stopwatch) for a steel ball bearing to fall from different heights (using a metre stick). Calculate a/g using g = 2s/t^(2).
