2. Title Lorem Ipsum
LOREM IPSUM DOLOR SIT
AMET, CONSECTETUER
ADIPISCING ELIT.
NUNC VIVERRA IMPERDIET
ENIM. FUSCE EST. VIVAMUS A
TELLUS.
PELLENTESQUE HABITANT
MORBI TRISTIQUE SENECTUS
ET NETUS.
3. OBJECTIVES
• Define momentum
• Draw simple diagrams to represent momentum as a
vector
• Calculate the momentum of a moving object
4. Revision – Newton's laws
• Newton’s Second Law:
• The resultant force acting on a body will cause the body to accelerate in the direction
• of the resultant force The acceleration of the body is directly proportional to the
• magnitude of the resultant force and inversely proportional to the mass of the object.
5. Newton’s Third Law:
If body A exerts a force on
body B then body B will exert
an equal but opposite force
on body A.
6. MOMENTUM
• Momentum The linear momentum of a particle (object) is a vector quantity equal to
the product of the mass of the particle (object) and its velocity.
• ⃗ p=m ⃗ v SI units kg ms-1
• Momentum and Newton's second law The net or resultant force acting on an object
is equal to the rate of change of momentum. F net = Δ P/t Δ
7. Change in momentum
Particles or objects can collide with other particles or objects, we know that this will often change their velocity (and
maybe their mass) so their momentum is likely to change as well. We will deal with collisions in detail a little bit later
but we are going to start by looking at the details of the change in momentum for a single particle or object.
Case 1: Object bouncing off a wall
Lets start with of , a ball of mass, m, moving with initial velocity, v⃗ i, to the right towards a wall. It will have
momentum p⃗ i=mv⃗ i to the right as shown in this picture:
The ball bounces off the wall. It will now be moving to the left,
with the same mass, but a different velocity, v⃗ fv→f and
therefore, a different momentum, p⃗ f=mv⃗ fp→f=mv→f, as
shown in this picture:
8. f we put this all together we can show the sequence and the
change in momentum in one diagram:
Δp⃗ =p⃗ f−p⃗ i
9. Conservation of momentum
A system is a physical configuration of particles and or objects that we study.
An isolated system is a physical configuration of particles and or objects that we study that doesn’t exchange
any matter with its surroundings and is not subject to any force whose source is external to the system.
Principle of conservation of linear momentum:
‘The total linear momentum of an isolated system is constant’ or ‘In an isolated system the total momentum
before a collision (or explosion) is equal to the total momentum after the collision (or explosion)’.
p⃗T=p⃗1+ p⃗2+ p⃗3+ … + p⃗
11. Impulse
Impulse is the product of the net force and the time interval for which the force acts.
Impulse=F⃗ net⋅Δ t
Impulse-momentum theorem
Impulse-momentum theorem: the impulse is equal to the change in momentum.
Impulse=Δ⃗p
12. ASSESSMENT
A moving bus has a momentum of of 48 000 kg-m-s-1. it is moving at a speed
of 15 m-s-1. what is its mass, in kg?
- 3.13x10 -4
- 3.20x10^3
- 6.12x10^4
- 7.20x10^5
13. Assessment
• A ball is thrown against a wall with a momentum 2p. It bounces perpendicularly
back along the same path with a momentum p. If we take the direction towards the
wall as positive, then the ball’s change in momentum is:
• a. 0
• b. p
• c. 3p
• d. −3p
14. Assessment
• An object of mass m is moving with a momentum p. Its velocity is v. For an object of mass 4m to have the
same momentum, its velocity must be:
• v/4
• v/2
• 2v
• 4v
16. REFERENCES
1 Siyavula . (2015) Physical Science Grade 12 Book. Available Online As
Https://Www.Everythingmaths.Co.Za/Read/Science/Grade-12/Momentumand-impulse
• 2 Trujll, R. (2008) Lecture Ch 07. Available From Slide Share As
Https://Www.Slideshare.Net/Rtrujill/Lecture-ch-07?Qid=b5c0f146-9c14-
472e-be3f-9dfeeb4b4c55&v=&b=&from_search=12
• 3 Poilek, J. (2014) Physics-chapter 6_momentum And Collisions. Available
From Slideshare As Https://Www.Slideshare.Net/Jpoilek/Chapter-6-
41402912?Next_slideshow=2
• 4 Srinivasan, S. (2015) Collisions. Available From Slideshare As
Https://Www.Slideshare.Net/Shyleshsrinivasan/Collisions49920064?Next_slideshow=3
• 5 Sciencepowerpoin. (2013) Potential And Kinetic Energy. Available From
Slideshare As
Https://Www.Slideshare.Net/Sciencepowerpointcom/Potential-and-kinetic
