GCSE Physics Revision "Acceleration 2"
Summary
TLDRThis educational video from 'Three Sighs' teaches viewers how to calculate the velocity of an object with constant acceleration and describes the acceleration of objects falling through fluids. It explains the formula for constant acceleration and provides sample problems involving cars, cyclists, and trains, demonstrating how to rearrange the equation for different scenarios. The video also introduces the concept of terminal velocity, explaining how objects fall towards Earth and reach a constant velocity due to air resistance, and emphasizes the importance of understanding this phenomenon for various objects in different fluids.
Takeaways
- 📚 The video is an educational tutorial on calculating velocity and acceleration for objects under constant acceleration.
- 🔍 The formula for acceleration is revisited: acceleration equals the change in velocity divided by time.
- 📐 An alternative equation is introduced for objects accelerating at a constant rate: final velocity squared minus initial velocity squared equals two times acceleration times distance.
- 📝 This equation will be provided in the exam, so students do not need to memorize it, but it might be more likely on the higher tier exam.
- 🚗 A sample problem is solved involving a car accelerating from 8 m/s to 12 m/s, with the distance traveled calculated to be 20 meters.
- 🚴 A challenge problem is presented for viewers to calculate the acceleration of a cyclist over a 50-meter distance, resulting in an acceleration of 0.16 m/s².
- 🚆 Another problem involves calculating the final velocity of a train after accelerating over a 50-meter distance, leading to a final velocity of 30 m/s.
- 🌍 The video discusses the acceleration of objects falling towards the Earth, with an initial acceleration due to gravity of approximately 9.8 m/s².
- 🪂 The concept of terminal velocity is introduced, where air resistance balances the force of gravity, leading to a constant velocity.
- 💨 Terminal velocity varies depending on the object and the force of friction it experiences, which is influenced by its shape.
- 📚 The video concludes with a note that there are many questions on acceleration in the provided revision book, accessible via a link.
Q & A
What is the formula for calculating acceleration?
-The formula for calculating acceleration is acceleration equals the change in velocity divided by the time (a = Δv/Δt).
What is the alternative equation for calculating the velocity of an object accelerating at a constant rate?
-The alternative equation is the final velocity squared minus the initial velocity squared equals two multiplied by the acceleration multiplied by the distance (v_f^2 - v_i^2 = 2ad).
Is it necessary to memorize the alternative equation for constant acceleration?
-No, you are given this equation in the exam, so you don't need to learn it by heart.
What is the expected initial acceleration of an object falling towards the Earth due to gravity?
-The initial acceleration of an object falling towards the Earth is approximately 9.8 meters per second squared.
What is the term used to describe the constant velocity an object reaches when falling through a fluid?
-The term is 'terminal velocity'.
What is the force that balances the force of gravity and causes an object to stop accelerating when falling through a fluid?
-The force that balances gravity and causes the object to stop accelerating is air resistance, or more generally, fluid resistance.
How does the shape of an object affect its terminal velocity?
-The shape of an object affects its terminal velocity by influencing the force of friction it experiences with the fluid it is falling through; objects with shapes that create more friction will have a lower terminal velocity.
In the sample question, what is the acceleration of the car if it goes from 8 m/s to 12 m/s?
-The acceleration of the car is 2 meters per second squared (2 m/s^2).
What is the acceleration of a cyclist who goes from 3 m/s to 5 m/s over a distance of 50 meters?
-The acceleration of the cyclist is 0.16 meters per second squared (0.16 m/s^2).
If a train accelerates from 20 m/s to a final velocity over a distance of 50 meters with an acceleration of 5 m/s^2, what is the final velocity?
-The final velocity of the train is 30 meters per second (30 m/s).
Where can I find more practice questions on acceleration?
-You can find more practice questions on acceleration in the revision world book, accessible through the provided link.
Outlines
📚 Introduction to Calculating Constant Acceleration
This paragraph introduces the video's focus on calculating the velocity of an object with constant acceleration. It emphasizes that viewers should be able to describe the acceleration of objects falling through a fluid by the end. The video builds on the previous lesson on acceleration, reminding viewers of the formula for calculating acceleration. It introduces a new formula for constant acceleration, which is provided in the exam, and suggests that it might be more challenging and thus more likely to appear on higher-level exams. The paragraph ends with a teaser for a sample question involving a car's acceleration.
🔍 Detailed Explanation of Constant Acceleration Equation
The paragraph provides a detailed explanation of the constant acceleration equation, which relates final velocity, initial velocity, acceleration, and distance. It clarifies that the equation will be provided in the exam, so memorization is unnecessary. The paragraph also suggests that the concept might be challenging, hinting at its appearance more in higher-tier exams. A step-by-step solution to a sample problem involving a car's acceleration is presented, demonstrating how to rearrange and use the equation to find the distance traveled.
🚴♂️ Applying the Acceleration Equation to a Cyclist
This section presents a practical application of the acceleration equation with a scenario involving a cyclist. It encourages viewers to pause the video and attempt to solve the problem independently before providing the solution. The paragraph outlines the given velocities and distance, and then shows how to plug these values into the equation to calculate the cyclist's acceleration, reinforcing the learning with a hands-on example.
🚆 Calculating Final Velocity of a Train with Given Acceleration
The paragraph shifts focus to calculating the final velocity of a train, given its initial velocity, acceleration, and distance traveled. It invites higher-tier students to rearrange the equation themselves, while reassuring foundation-tier students that the equation will be provided. After a brief pause for viewers to attempt the calculation, the paragraph presents the rearranged equation and guides through the process of finding the train's final velocity using the given values.
🪂 Understanding Terminal Velocity and Acceleration Due to Gravity
The final paragraph explores the concept of terminal velocity, particularly in the context of a skydiver falling towards Earth. It explains that objects initially accelerate due to gravity at approximately 9.8 m/s² but eventually reach a point where air resistance balances the force of gravity, leading to a constant velocity known as terminal velocity. The paragraph highlights the dependency of terminal velocity on the object's characteristics, such as shape, which affects the force of friction experienced. It concludes by directing viewers to additional resources for practice, emphasizing the importance of understanding acceleration in various contexts.
Mindmap
Keywords
💡Velocity
💡Acceleration
💡Constant Rate
💡Equation
💡Sample Question
💡Distance
💡Terminal Velocity
💡Fluid
💡Air Resistance
💡Force of Gravity
💡Revision World
Highlights
The video teaches how to calculate the velocity of an object with constant acceleration.
An alternative equation for calculating acceleration is provided, which may be included in exams.
The equation for constant acceleration is: final velocity squared minus initial velocity squared equals two times acceleration times distance.
Students are advised not to memorize the equation as it will be provided in the exam.
The equation might be more suitable for higher-tier exams, but foundation tier students are encouraged to watch the video.
A sample question is presented involving a car accelerating from 8 m/s to 12 m/s to calculate the distance traveled.
The equation is rearranged to solve for distance, with given values plugged in to find the result.
A challenge question asks to calculate the acceleration of a cyclist over a 50-meter distance.
The equation is rearranged again for the viewers to solve the cyclist's acceleration problem.
A train's final velocity is calculated after accelerating over a 50-meter distance with a given initial velocity.
Higher-tier students are encouraged to rearrange the equation themselves for the train's final velocity problem.
The concept of terminal velocity is introduced, which is the constant velocity an object reaches when falling through a fluid.
Terminal velocity is achieved when air resistance balances the force of gravity.
The terminal velocity depends on the object's shape and the frictional force it experiences.
The video mentions that terminal velocity applies to objects falling through any fluid, not just air.
The video concludes by directing viewers to a revision book for more practice on acceleration problems.
Transcripts
[Music]
hi and welcome back to three sighs
lessons Cole you K by the end of this
video you should be able to calculate
the velocity of an object which is
accelerating at a constant rate you
should then be able to describe the
acceleration of an object falling
through a fluid in the last video we
looked at acceleration we calculate
acceleration using this equation
acceleration equals a change in velocity
divided by the time and remember you're
not in this equation in the exam now if
an object accelerating at a constant
rate then we can use a different
equation and I'm showing you that here
the final velocity squared minus the
initial velocity squared equals two
multiplied by the acceleration
multiplied by the distance now I want to
make a couple of points about this
firstly you are given this equation in
the exam so you don't need to learn it
secondly this is pretty tricky so I
think it's more likely to appear on the
higher paper than the foundation I could
be wrong though
so if you're a foundation tier student
then you do need to keep watching but
please don't panic over this equation
also you should pay close attention to
the second part of the video as that's
more straightforward here's a sample
question a car is driving at a velocity
of 8 meters per second it accelerates by
2 meters per second squared to a final
velocity of 12 meters per second
calculate the distance traveled okay so
here's the equation and we're
calculating the distance to do that we
need to rearrange the equation like this
the final velocity was 12 meters per
second and the initial velocity was 8
meters per second the acceleration was 2
meters per second squared
putting these numbers into the equation
gives us a distance traveled of 20
meters here's a question for you to try
a cyclist is moving at a velocity of 3
meters per second and accelerates to 5
meters per second over a distance of 50
meters calculate the acceleration of the
cyclist now for this question have we
arranged the equation for you so pause
the video now and try this yourself
okay so the initial velocity is three
meters per second and the final velocity
is five meters per second the distance
travel is 50 meters putting these into
the equation it gives us an acceleration
of nought point one six meters per
second squared
here's a final question for you a train
has an initial velocity of 20 meters per
second it accelerates at five meters per
second squared over a distance of 50
meters calculate the final velocity now
in this case I'd like you to rearrange
the equation yourself if a higher tier
student then you should be able to do
this if you're a foundation tier student
then don't worry because I'll be giving
you the equation in a second okay so
here's the rearranged equation to
calculate the final velocity I'd like
you to pause the video now and carry out
this calculation okay the initial
velocity is 20 meters per second and the
acceleration is 5 meters per second
squared the distance is 50 meters put in
the numbers into the equation gives us a
final velocity of 30 meters per second
okay we're going to finish now by
looking at how objects accelerate
towards the Earth I'm showing you have a
skydiver who has just jumped out of an
airplane
now the key fact is that when any object
Falls towards the surface of the earth
it initially accelerates at around 9.8
meters per second squared this
acceleration is due to the force of
gravity acting on the object
now as the skydiver Falls he experiences
an upward force of friction with the air
particles this is called air resistance
and after some time the force of air
resistance balances the force due to
gravity at this point the object stops
accelerating and moves at a constant
velocity scientists call this the
terminal velocity and you need to learn
that expression this applies to any
object falling through a fluid in the
case of the skydiver the fluid is air
but we see the same effect with an
object falling through a liquid now the
terminal velocity that the object
reaches depends on the object some
objects experience a greater force of
friction due to their shape so they will
have
lower terminal velocity remember you'll
find plenty of questions on acceleration
in my revision world book and you can
get that by clicking on the link above
[Music]
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