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Newtonian Revolution: Mechanics Is The Branch of Physics That Focuses On The Motion

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Elah Palaganas

The document discusses key concepts in mechanics including speed, velocity, acceleration, scalars and vectors. It defines important terms like displacement, average speed, instantaneous speed, and acceleration. Examples are provided to illustrate these concepts, such as calculating average speed from distance and time, determining acceleration from changes in velocity over time, and distinguishing between distance, displacement, and deceleration.

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Newtonian Revolution: Mechanics Is The Branch of Physics That Focuses On The Motion

Uploaded by

Elah Palaganas
58 views12 pages
The document discusses key concepts in mechanics including speed, velocity, acceleration, scalars and vectors. It defines important terms like displacement, average speed, instantaneous speed, and acceleration. Examples are provided to illustrate these concepts, such as calculating average speed from distance and time, determining acceleration from changes in velocity over time, and distinguishing between distance, displacement, and deceleration.

Original Title

Describing Motion

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The document discusses key concepts in mechanics including speed, velocity, acceleration, scalars and vectors. It defines important terms like displacement, average speed, instantaneous speed, and acceleration. Examples are provided to illustrate these concepts, such as calculating average speed from distance and time, determining acceleration from changes in velocity over time, and distinguishing between distance, displacement, and deceleration.

Copyright:

© All Rights Reserved
Download as PPT, PDF, TXT or read online from Scribd
Download as ppt, pdf, or txt
58 views12 pages

Newtonian Revolution: Mechanics Is The Branch of Physics That Focuses On The Motion

Uploaded by

Elah Palaganas
The document discusses key concepts in mechanics including speed, velocity, acceleration, scalars and vectors. It defines important terms like displacement, average speed, instantaneous speed, and acceleration. Examples are provided to illustrate these concepts, such as calculating average speed from distance and time, determining acceleration from changes in velocity over time, and distinguishing between distance, displacement, and deceleration.

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Newtonian Revolution

The study of Physics begins with Newtonian mechanics.


Mechanics is the branch of physics that focuses on the motion
of objects and the forces that cause the motion to change.
There are two parts to mechanics: Kinematics and Dynamics.
Kinematics deals with the concepts that are needed to describe
motion, without any reference to forces.
Chapter 2: Describing Motion
Chapter 3: Falling Objects and Projectile Motion
Dynamics deals with the effect that forces have on motion
Chapter 4: Newton’s Laws-Explaining motion
Chapter 2
Describing Motion
• Speed: Average and Instantaneous
• Velocity
• Acceleration
• Graphing motion
Average Speed
Average speed equals the distance traveled divided by
the time of travel.
dis tan ce
AverageSpeed  .
time
d
aS  .
t
Unit: MPH, kmPH, m/s
Speed calculation:
Instantaneous Speed
http://www.physicsclassroom.com/
mmedia/kinema/trip.cfm

d
iS  .
t
Unit Conversion:
Velocity = Speed with Direction

Velocity can be changed by


changing speed or direction
or both.
Vectors and Scalars
Physics deals with many physical quantities, which are divided
into scalars and vectors.
A scalar quantity is one that can be described by a single
number (including any units) giving its size or magnitude.
Examples: Distance, Time, volume, mass, temperature, and
density.
A quantity that deals with both magnitude and direction is
called a vector quantity.
Examples: Displacement, Force, weight, and velocity.
Distance and Displacement
Starting from origin, O a person walks 90-m east, then turns
around and walks 40-m west.

Q: What is the total walked distance? A: 130-m


Q: What is the displacement? A: 50-m, due east.
Scalars and Vectors

Scalar Vector
Distance (m) Displacement (m)

Speed (m/s) Velocity (m/s)

Mass (kg) Weight (N)


Acceleration
• Acceleration is the rate at which velocity
changes.
v v  v0
a 
t t
Acceleration is a vector quantity.
Unit of acceleration: m/s2

Acceleration of a sports car:


http://www.cars.com/go/crp/buyingGuides/Story.jsp?
section=Sports&story=sportsQuickest&subject=stories&referer=&year=2005
Deceleration or
Negative Acceleration
An object speeds up when the acceleration and velocity vectors
point in the same direction.
Whenever the acceleration and velocity vectors have opposite
directions, the object slows down and is said to be “decelerating.”

V1 = 20 m/s due east


V2 = 10 m/s due east
t = 2.0 s
a=?
Can a Car Be Accelerating When
Its Speed Is Constant?
Exercises and Problems
1. A person covers a distance of 320 miles in a travel time of 8 hours.
What is the average speed for this trip?

2. A car travels with an average speed of 55 miles/hr. What is this


speed in m/s?

3. The velocity of a car moving in a straight line increases from 8 m/s


to 22 m/s in 7 seconds. What is the average acceleration of the car
during this period?

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