GCSE Physics Revision "Acceleration"
Summary
TLDRThis video from Free Size Lessons teaches the concept of acceleration, guiding viewers through its definition and calculation. It explains that acceleration is the change in velocity over time, using the formula a = Δv/Δt. The video provides examples, including a car's deceleration and a cyclist's acceleration, and introduces how to determine an object's acceleration from a velocity-time graph. It also covers calculating distance traveled from the area under the graph, offering tips for both constant and variable acceleration scenarios. The video concludes with a resource for further practice.
Takeaways
- 📚 The video is a physics lesson focusing on the concept of acceleration.
- 🚗 Acceleration is defined as the change in velocity over a given time and is calculated using the formula: acceleration = (final velocity - initial velocity) / time.
- 📉 A negative acceleration indicates deceleration, which is when an object is slowing down.
- 📈 The gradient of a velocity-time graph represents the acceleration of an object, with a horizontal line indicating constant velocity, an upward slope indicating acceleration, and a downward slope indicating deceleration.
- 📊 The total area under a velocity-time graph represents the distance traveled in a specific direction, which is the displacement.
- 🔢 For a graph with constant acceleration or deceleration, the total area can be calculated by dividing the graph into geometric shapes and summing their areas.
- 📐 In cases where the acceleration or deceleration is not constant, the total area under the graph is estimated by counting squares or estimating partial squares.
- 🚴♂️ An example problem involves calculating the acceleration of a cyclist whose velocity decreases from six meters per second to zero over 12 seconds, resulting in a negative acceleration.
- 🚗 Another example problem involves calculating the acceleration of a car that slows from 50 meters per second to 35 meters per second over 20 seconds, resulting in a positive acceleration.
- 📚 The video script emphasizes the importance of learning and memorizing the formula for acceleration as it may not be provided in an exam.
- 🔗 The video suggests additional practice with acceleration problems on velocity-time graphs can be found in the instructor's vision workbook, which is accessible through a provided link.
Q & A
What is the main topic of the video?
-The main topic of the video is acceleration, including its definition, calculation, and how to determine it from a velocity-time graph.
What is the formula for calculating acceleration?
-The formula for calculating acceleration is acceleration (in meters per second squared) equals the change in velocity (in meters per second) divided by the time (in seconds).
What is the significance of the gradient on a velocity-time graph?
-The gradient of a velocity-time graph represents the acceleration of an object. A horizontal line indicates constant velocity, an upward sloping line indicates acceleration, and a downward sloping line indicates deceleration.
How can you calculate the distance traveled by an object using a velocity-time graph?
-The total area under the velocity-time graph represents the distance traveled in a specific direction, which is the displacement. For constant acceleration or deceleration, the graph can be divided into geometric shapes to calculate the total area.
What is the difference between acceleration and deceleration?
-Acceleration is the rate at which an object's velocity increases, while deceleration is the rate at which an object's velocity decreases. Deceleration is often represented by a negative acceleration value.
In the example of the car, what is the final velocity after accelerating from 50 m/s north to 35 m/s north over 20 seconds?
-The final velocity of the car is 35 meters per second north.
What is the acceleration of the cyclist who slows down from 6 m/s east to 0 m/s over 12 seconds?
-The acceleration of the cyclist is -0.5 meters per second squared, indicating deceleration.
How do you calculate the acceleration from the first part of the velocity-time graph shown in the video?
-You calculate the acceleration by subtracting the initial velocity from the final velocity and dividing by the time taken, which in the example is (15 m/s - 0 m/s) / 100 s = 0.15 m/s².
What is the total displacement calculated from the area under the velocity-time graph with constant acceleration or deceleration?
-In the example given, the total displacement is the sum of the areas of the geometric shapes, which is 4,500 meters.
How can you estimate the total distance traveled when the acceleration and deceleration are not constant in a velocity-time graph?
-When acceleration and deceleration are not constant, you can estimate the total distance by counting the number of squares and estimating the area of partial squares, then multiplying by the area of each square.
What resource is mentioned in the video for additional practice on acceleration problems involving velocity-time graphs?
-The video mentions a vision workbook with plenty of questions on acceleration and velocity-time graphs, which can be accessed by clicking on the provided link.
Outlines
📚 Introduction to Acceleration and Calculation
This paragraph introduces the concept of acceleration as the rate of change of velocity over time. It explains that acceleration is a vector quantity, meaning it has both magnitude and direction, and is calculated using the formula: acceleration = (change in velocity) / time. The paragraph also provides a typical example of calculating acceleration for a car that decelerates from 50 m/s to 35 m/s over 20 seconds, resulting in an acceleration of 1 m/s². Additionally, it presents a second example involving a cyclist who comes to a stop from an initial velocity of 6 m/s in 12 seconds, illustrating deceleration with an acceleration of -2.5 m/s². The paragraph concludes with an introduction to calculating acceleration from a velocity-time graph, emphasizing that the gradient of the graph represents acceleration.
📈 Using Velocity-Time Graphs for Acceleration and Displacement
This paragraph delves deeper into the use of velocity-time graphs for determining both acceleration and displacement. It clarifies that a horizontal line in the graph indicates constant velocity, an upward slope indicates acceleration, and a downward slope indicates deceleration. The paragraph provides a step-by-step method to calculate acceleration from the graph by finding the gradient between points. It also explains how to calculate the total distance traveled by an object by estimating the area under the graph, either by counting complete squares or estimating partial squares, as demonstrated with an example where the total displacement is calculated to be 5,000 meters. The paragraph encourages high-tier students to continue learning and reminds them of additional practice questions available in the provided workbook.
Mindmap
Keywords
💡Acceleration
💡Velocity
💡Deceleration
💡Meters per second squared
💡Velocity-time graph
💡Gradient
💡Displacement
💡Constant acceleration
💡Non-constant acceleration
💡Free Size Lessons
💡High tier student
Highlights
Introduction to the concept of acceleration and its calculation.
Velocity defined as speed in a given direction with both magnitude and direction.
Acceleration is the change in velocity over time, calculated using a specific formula.
The importance of memorizing the acceleration formula for exams.
Example problem: Calculating the acceleration of a car traveling north.
Explanation of how to calculate acceleration with a decrease in velocity.
Introduction of deceleration as a form of negative acceleration.
Using a velocity-time graph to determine an object's acceleration.
The significance of the gradient in a velocity-time graph representing acceleration.
Example calculation using a velocity-time graph for constant acceleration.
Method to calculate the total area under a velocity-time graph for distance traveled.
Approach for estimating the total area under a non-uniform acceleration graph.
The concept of dividing the graph into shapes for area calculation in constant acceleration scenarios.
Explanation of counting squares for area estimation in non-uniform acceleration graphs.
Final calculation example for total displacement using the area under a velocity-time graph.
Mention of additional practice questions available in the instructor's workbook.
Transcripts
[Music]
I'm welcome back to free size lessons
code okay by the end of this video you
should be able to describe what's meant
by acceleration you should then be able
to calculate the acceleration of an
object and if you're a high tier student
then you should be able to calculate the
distance traveled by an object from a
velocity time graph in a previous video
we looked at the idea of velocity the
velocity of an object is its speed in a
given direction velocity is a vector
quantity as it has both magnitude and
direction the acceleration of an object
tells us the change in its velocity over
a given time and we calculate
acceleration using this equation
acceleration in meters per second
squared equals the change in velocity
and meters per second divided by the
time in seconds I've also given me the
triangle for this equation now you're
not given this equation in the exam so
you need to learn it here's a typical
question a car is traveling at a
velocity of 50 meters per second north
it accelerates to a velocity of 35
meters per second north in 20 seconds
calculate the acceleration of the car so
pause the video now and try this
yourself okay so to calculate
acceleration we divided the change in
velocity by the time taken the final
velocity was 35 meters per second north
and the start velocity was 50 meters per
second north so the change in velocity
is 35 minus 15 giving us a value of 20
meters per second the time taken was 20
seconds putting these into the equation
gives us an acceleration of one meter
per second squared so what that means is
that the car increased its velocity by
one meter per second every second over a
twenty second period try this question a
cyclist is traveling at the velocity of
six meters per second east a velocity
reduces to zero and 12 seconds calculate
the acceleration of the cyclist again
pause the video and try this yourself
okay the acceleration equals the change
in velocity divided by the time taken
the final velocity was zero meters per
second East and the start velocity was
six meters per second east so the change
in velocity is zero minus six meters per
second
this gives us a change in velocity of
minus six meters per second
this took place over 12 seconds putting
these into the equation it gives us an
acceleration of minus not 25 meters per
second squared in this case the object
slowing down and scientists call this
deceleration now we can also calculate
the acceleration of an object using a
velocity time graph so we're going to
look at those now I'm showing you a
velocity time graph here and you could
be asked to plot one of these in your
exam our key fact is that the gradient
of a velocity time graph tells us the
acceleration of the object in the case
of a horizontal line like this the
objects traveling at a constant velocity
an upward sloping line shows that the
object's accelerating whereas a downward
sloping line shows that the object is
decelerating so we're going to calculate
the acceleration in the first part of
the graph to do that we subtract the
initial velocity from the final velocity
under vide in this case the final
velocity is 15 meters per second and the
initial velocity was zero and the time
is 100 seconds putting these into the
calculation gives us an acceleration of
naught point one five meters per second
squared
looking at the last part of the graph we
can see that the final velocity is zero
and the initial velocity was fifteen
meters per second the time was 300
seconds pudding listen to the
calculation gives us an acceleration of
minus naught point naught five meters
per second squared in this case the
negative number tells us that the object
was decelerating
okay now foundation tier students can
stop watching however high attea
students need to continue so as we've
seen the gradient of a velocity time
graph tells us the acceleration however
the total area under the graph tells us
the distance traveled in a specific
direction in other words the
displacement
now when we see constant acceleration or
deceleration then we simply divide the
graph into shapes and calculate the
total area so we've got a triangle with
an area of 750 a rectangle with an area
of 1500 and a triangle with an area of
2,250 adding these together gives us a
total distance or displacement of 4,500
meters now you might see a velocity time
graph like this in this case the
acceleration and deceleration are not
constant to calculate the total area
under the graph we need to count squares
in this case there are 15 complete or
almost complete squares we then have to
estimate the total of the parts of
squares these are up to approximately 5
squares so the total number of squares
under the graph is 20 each square has an
area of 250 multiplying 20 by 250 gives
us a total distance or displacement of
5,000 meters remember you'll find plenty
of questions on acceleration on velocity
time graphs in my vision workbook and
you can get that by clicking on the link
above
[Music]
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