motion speed: average and instantaneous velocity acceleration
TRANSCRIPT
Motion
• Speed: average and instantaneous
• Velocity
• Acceleration
Speed Average and Instantaneous
Let’s Go to Myrtle Beach
Average Speed
Average speed equals the distance traveled divided by the time of travel.
.t
ds
Instantaneous Speed
Scalars and Vectors
Many physical quantities are used in physics, 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: Time interval, distance, speed, volume, mass, temperature, and density.
A quantity that deals inherently with both magnitude and direction is called a vector quantity.
Examples: Force, weight, velocity, and displacement.
Scalars and Vectors
Scalar Vector
Distance Displacement
Speed Velocity
Mass Weight
Vector Illustration
The length of the vector arrow is proportional to the magnitude of the vector and the arrow represents the direction.
In the text, bold face is used for vectors and italics is used for scalars. When hand written an arrow is placed above the symbol.
Consider the following displacement vector of a car:
Velocity
Velocity is a vector.
Velocity = Speed + Direction
Acceleration
Have you experienced acceleration?
Acceleration
• Acceleration is the rate at which velocity changes.
t
vv
t
va 0
Acceleration
Positive Acceleration
Negative Acceleration
Can a Car Be Accelerating When Its Speed Is Constant?
Acceleration of a Sports Car
• http://www.cars.com/go/crp/buyingGuides/Story.jsp?section=Sports&story=sportsQuickest&subject=stories&referer=&year=2005
Free Fall
Acceleration due to gravity affects the velocity of an object as it falls.