Momentum and Impulse | Grade 9 Science Quarter 4 Week 3 Lesson
Summary
TLDRThis engaging video lesson from the Strong Techie YouTube channel dives into the concepts of momentum and impulse, particularly relevant for Grade 9 Science students during Quarter 4, Week 3. The host sets clear learning objectives to examine the effects of collisions and predict related damages or injuries, while also connecting these phenomena to the momentum and impulse of colliding objects. Using relatable examples from basketball and driving scenarios, the video explains momentum as the product of mass and velocity, symbolized as p = m × v. It further explores how changes in velocity, such as those experienced by a bus navigating a curvy road, lead to changes in momentum, which are quantified as impulse. Impulse is defined as the product of force and time of contact, and is crucial in understanding how collisions affect objects. The video also illustrates how the force of impact can be influenced by momentum and contact time, with practical implications such as the design of airbags in cars. Sample problems are solved to demonstrate the calculation of momentum and the determination of force exerted during a football pass. The lesson concludes with scenarios that demonstrate the relationship between impulse and momentum, emphasizing that a greater change in momentum corresponds to a greater impulse. The video is an informative resource for understanding the principles of momentum and impulse in the context of motion and collisions.
Takeaways
- 📚 The concept of momentum is introduced as mass in motion, mathematically expressed as p = m * v, where p is momentum, m is mass, and v is velocity.
- 🏀 Momentum is related to the game of basketball, illustrating how a team's momentum can affect the outcome of a match.
- 🛒 Sample problem solving demonstrates how to calculate the momentum of a moving object, such as a grocery cart.
- 🚫 An object at rest has zero momentum, since velocity is zero.
- 🚌 Real-world scenarios, like a bus on a curvy road, are used to explain changes in velocity and consequently, momentum.
- 📉 A decrease in the mass of a moving object, such as passengers getting off a bus, results in a decrease in momentum.
- 📈 Impulse is defined as the change in momentum, which requires a force to change the momentum of an object.
- ⚖️ Impulse is calculated as the product of force and time (I = F * t), and it's directly proportional to the change in momentum.
- 💥 Collisions, both elastic and inelastic, are a way in which objects can change their momentum.
- 🤾♂️ An example of calculating the average force exerted by a player passing a football is provided to illustrate the concept of impulse.
- 🚗 The impact force in a collision is directly proportional to the momentum of the colliding body and inversely proportional to the time of contact.
- 💡 Airbags in cars are designed to extend the time of contact during a collision, thereby reducing the impact force and potentially preventing injuries.
Q & A
What is the main topic of today's video lesson?
-Today's video lesson is about momentum and impulse.
What are the two factors that define momentum?
-The two factors that define momentum are mass and velocity of an object.
How is momentum mathematically expressed?
-Momentum is mathematically expressed as p = m * v, where p is momentum, m is mass, and v is velocity.
What is the unit for momentum?
-The unit for momentum is kilogram meter per second (kg·m/s).
What happens to the momentum of an object if it is not moving?
-If an object is not moving, its momentum is zero because its velocity is zero.
What is impulse and how is it related to momentum?
-Impulse is the change in momentum of a moving object and is equal to the product of force and time. It is the cause of a change in momentum.
How is impulse mathematically expressed?
-Impulse is mathematically expressed as I = F * t, where I is impulse, F is force, and t is time.
What is the standard unit for impulse?
-The standard unit for impulse is newton second (N·s) or kilogram meter per second (kg·m/s).
How does the time of contact affect the impact force during a collision?
-The impact force is inversely proportional to the time of contact. Extending the time of contact can decrease the impact force.
Why are cars designed with airbags?
-Cars are designed with airbags to extend the time of contact during a collision, which decreases the impact force and can prevent or lessen injuries.
What is the relationship between impulse and the change in momentum during a collision?
-The change in momentum is equal to the impulse experienced by an object. A greater change in momentum results in a greater impulse.
What happens to the mass of objects involved in a collision?
-The mass of objects involved in a collision does not change. The change is in their velocity and momentum.
Outlines
📚 Introduction to Momentum and Impulse
This paragraph introduces the topic of momentum and impulse in the context of a grade 9 science lesson. It sets the learning objectives to examine the effects of collisions and to relate impulse and momentum to the collision of objects. The video encourages students to listen carefully and take notes. It uses basketball as an example to illustrate the concepts, explaining that momentum is the product of mass and velocity (p = m * v). A sample problem is provided to calculate the momentum of a grocery cart, and the concept of zero momentum for a stationary object is discussed. The paragraph also explores what happens to a bus's velocity when it travels on a curvy road and then a straight road, and how the mass of the bus changes when passengers get on and off.
🏈 Impulse and Its Relation to Momentum
The second paragraph delves into the concept of impulse, which is defined as the change in momentum. It explains that when an object's velocity changes, its momentum changes, and this change is referred to as impulse (i = Δp). Impulse is also described as the product of force and time (i = F * t). A sample problem calculates the average force exerted by an offensive player passing a football, using the given mass, velocity, and time of contact. The paragraph further discusses how the impact force is related to the momentum of the body and the time of contact, using the example of a car crash and airbags to illustrate how extending the time of contact can decrease the impact force.
💥 Collisions and the Effects on Momentum
The final paragraph provides example scenarios to demonstrate the concept of impulse. It clarifies that an object moving with constant momentum has zero impulse, as there is no change in momentum. The paragraph presents a billiard game scenario to discuss the changes in mass, velocity, and momentum of the cue ball and another ball after a collision. It emphasizes that a change in velocity results in a change in momentum and thus an impulse. Another scenario involving two cars of equal mass colliding is used to show that the car with a greater change in velocity experiences a greater change in momentum and therefore a greater impulse. The paragraph concludes with a recap of the concepts learned and an invitation to continue the discussion in the next video lesson.
Mindmap
Keywords
💡Momentum
💡Impulse
💡Projectile Motion
💡Collision
💡Velocity
💡Mass
💡Force
💡Time of Contact
💡Elastic and Inelastic Collisions
💡Airbags
💡Sample Problem
Highlights
Today's video lesson is about momentum and impulse, and how they relate to collisions of objects.
Momentum is defined as mass times velocity, representing the quantity of motion of an object.
An object with mass that is moving has momentum, while a stationary object has zero momentum.
Impulse is the change in momentum, which occurs when an object's velocity changes due to a force.
Impulse can be calculated as the product of force and the time of contact between two objects.
Bodies change their momentum through collisions, which can be elastic or inelastic.
The impact force of a collision is directly proportional to the momentum of the colliding bodies and inversely proportional to the time of contact.
Cars are designed with airbags to extend the time of contact in a collision, thereby reducing the impact force on occupants.
In a game of billiards, when the cue ball collides with another ball, there is a change in momentum and impulse for both balls.
In a collision between two cars of equal mass, the car with the greater velocity will have a greater change in momentum and impulse.
The video uses examples from basketball and driving scenarios to illustrate the concepts of momentum and impulse.
The video provides a sample problem to calculate the momentum of a moving grocery cart.
The video explains how the mass and velocity of an object determine its momentum.
The video demonstrates how to calculate the average force exerted by a player kicking a football using the concept of impulse.
The video emphasizes that any change in an object's momentum is due to an impulse being applied.
The video discusses how collisions can result in either elastic or inelastic changes in momentum.
The video concludes by summarizing the key concepts of momentum and impulse and their relationship to collisions.
Transcripts
hello students
welcome back to my strong techie youtube
channel
if you haven't watched our video lesson
about projectile motion pause the video
and click the links in the description
box below today's video lesson is a new
topic grade 9 science quarter 4 week 3
lesson is all about momentum and impulse
here's our learning objectives
examine effects and predict causes of
collision related damages or injuries
and relate impulse and momentum to
collision of objects
so what are you waiting for listen
carefully and jot down notes as we learn
about momentum and impulse keep on
watching
[Music]
in the previous topic we talked about
projectile motion at this point you
already know how to describe the motions
and the relationship of the components
of a projectile now let us start with
momentum and impulse suppose you play
basketball with your friends what will
happen to the ball if it hits the board
instead of inside the ring
how about if you bump into another
player that is bigger than you
these questions will be answered as you
go along with this video lesson
one of the most common team sports is
basketball
imagine two teams who are involved in a
really tight tournament quarterfinals
team a has two points ahead of team b
later on in the match
a player from team b scores a three
point shot and followed by a series of
two point shots tim b couldn't stop
their momentum
and what do you mean by momentum
in our example a while ago these are the
things that we need to consider in
defining momentum first the object has a
mass and second the object is moving any
object with a quantity of matter has
momentum and momentum simply means mass
and motion it is equal to the product of
mass and velocity mathematically it is
expressed as p is equal to m times v
where p is the momentum in kilogram
meter per second
m is the mass of the moving object in
kilogram and v refers to the velocity of
the moving object in meter per second
let us try to solve this problem
sample problem 1 what is the momentum of
a 22 kilogram grocery cart which travels
at 1.2 meter per second first let us
have the given the mass of the grossery
cart is 22 kilograms it travels with the
velocity of 1.2 meter per second and we
are looking for the p or the momentum
here's our formula to get the momentum
we need to get the product of mass and
velocity now let us solve this problem
our solution p is equal to the mass
which is 22 kilograms the velocity which
is 1.2 meter per second multiplying
these two the product is
26.4 and the unit is kilogram meter per
second take note how you write the unit
for momentum and this is our final
answer
next
how about the momentum of an object that
is not moving
just like a car that is part
remember class if any object of any mass
is not moving it has zero momentum since
its velocity is zero let us consider
another situation and try to answer the
given questions
suppose you ride a bus from illegal city
to cagayan de oro what do you think will
happen to the bus after it passes along
a curvy road
will it slow down
will it speed up
or the velocity will not change at all
if your answer is letter a
then you are correct
the bus will slow down
if it passes along a curvy road
next question
after passing curvy road the bus travels
in a straight road
how will you describe the velocity of
the bus
it increases
decreases or not change at all
if your answer is letter a
then you are correct
after passing curvy road and travels a
straight road the velocity of the bus
will increase
next
there were only 25 passengers in the bus
along the way four passengers dropped at
lagunding and bus stop and another four
passengers dropped off at oppal bastapp
what can you say about the mass of the
bus it increases
decreases
or not change at all if your answer is
letter b then you are correct the mass
of the bus decreases
based on our example situation we can
say that when the object slows down or
moves faster its velocity decreases or
increases
if there is a change in the velocity of
the mass of an object there is also a
change in momentum and that change of
momentum is what we call
impulse
impulse is equal to the change in
momentum
and it is represented as letter i again
class
impulse is equal to the change in
momentum and remember class that
momentum is equal to the product of mass
and velocity
just like our example there is a change
in momentum and for that to happen force
is needed to change the momentum of a
body this force multiplied by the time
of contact is known as impulse impulse
is equal to the product of force which
is expressed as capital letter f and
time which is expressed as small letter
t analyzing these concepts class we can
say this equation
since impulse is equal to the change of
momentum
and momentum is the product of mass and
velocity
therefore we can say that
impulse is equal to the product of force
and time and mass and velocity the
standard unit for momentum and impulse
is newton second or
kilogram meter per second take note
class bodies change their momentum
through collisions which may be elastic
or inelastic let us have a sample
problem
sample problem number two an offensive
player passes a football of mass 0.42
kilogram with a velocity of
25.0 meter per second due south if the
player is in contact with the ball for
0.050 seconds what is the magnitude of
the average force he exerts
here are the given for our problem
the mass of the ball is 0.42 kilogram
its velocity is 25.0 meter per second
south
and the time contact with the ball is
0.050 seconds and we are looking for the
force remember class our formula for the
impulse impulse is equal to the product
of force and time which is also equal to
the product of mass and velocity since
we need to determine the force we can do
some algebra with this equation using
division property of equality let us
divide d both sides and we can cancel
out time on the left side of the
equation therefore we can get this
formula force is equal to the product of
mass and velocity divided by time now
let us solve this problem
for our solution let us substitute our
given to our formula force is equal to
the mass which is 0.42 kilogram
our velocity which is 25.0 meter per
second
all over our time which is 0.050
second
0.42 times
25.0 we have
10.5 in our unit kilogram meter per
second
divided by 0.050
seconds
dividing these the quotient will be
210 kilogram meter per second squared
and this is our final answer and that is
how you solve this kind of problem
rearranging our equation will help us
understand how impact force is affected
by the change in momentum and the time
of contact it shows that the force of
impact is directly proportional to the
momentum of the body and inversely
proportional to the time of contact we
can say for example that the impact
force of a fast moving car is higher and
therefore it can cause greater damage
after the collision than the car moving
at a lower velocity on the other hand
the equation also tells us that the
impact force could be decreased by
extending the time of contact that is
why cars are designed with air bugs
because it can lessen or prevent
injuries in the event of crash or
collision the inflation of the airbag is
initiated by crash sensors these
decreases the impact force by increasing
the time of contact next let's have some
example scenarios exhibiting impulse
what do you think is the impulse of an
object moving with constant momentum
constant means no change at all
therefore there is no impulse or zero
impulse for objects moving with constant
momentum take note of that class you now
know
that any object has momentum and it is
equal to the product of mass and
velocity
impulse on the other hand is a change of
momentum of a moving object next
what will happen to a moving object if
it collides with another object let's
have this scenario suppose you are
playing billiard
the cue ball and ball number one are
initially at rest
then you use the taco to hit ball number
one based on the given illustration
answer the following questions
what did you observe on the mass of the
cue ball before and after collision
there is no change in mass how about
ball number one
also there is no change in their mass
question number two
since it is initially at rest what are
the initial velocity of the balls
the answer
zero question number three
after collision is there a change in
velocity of the cue ball and ball number
one
the answer
yes
question number four
is there a change in momentum
of the cue ball and ball number one
and why
since there is a change in the velocity
of course there is a change in momentum
therefore
there is impulse
because there is a change in momentum
since the cue ball and ball number one
have a change in velocity after
collision then
both balls have a change in momentum
also in collisions an object that
experiences a greater change in momentum
has greater impulse
therefore this shows the relationship
between impulse and momentum that a
change in momentum is equal to impulse
let's have another scenario suppose that
two cars with equal masses collide with
each other car a travels faster than car
b
they both stop after collision note that
the bigger the letter of velocity or
mass the greater its value and in this
scenario the greater velocity is car a
now
given this scenario which of the two
cars has the greater change of velocity
the answer is car a
next
which car has the greater change in
momentum
explain your answer
the answer
car a because it travels faster than car
b therefore it has greater velocity
remember class greater velocity means
greater change in momentum next question
which car has the greater impulse
the answer is car a because it has
greater change in momentum in other
words the object that experience a
greater impulse is the one that has the
greater change in momentum and that ends
our lesson about impulse and momentum i
hope you learned something new and you
take note the concepts about impulse and
momentum we will continue discussing
this topic in our next video lesson so
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[Music]
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