29 terms

Motion

the change of position in time

Displacement

the directed change of an object's position

Velocity

the time rate of change of displacement

Acceleration

the time rate of change of velocity

Objects that fall freely near the surface of the Earth...

are uniformly accelerated by gravity

"Zero-time"

the time when we begin the event

"Zero-position"

the specific place where we begin measuring

Displacement in measured in...

units of length (such as meters or inches)

In the graph in Section 2.2 (pg 15), the displacement of the object between times t1 and t2 is given by the relationship

d=d2-d1 (we are not primarily concerned about the exact path taken by the object between these points. We assume that the magnitude of the displacement is given by the length of a straight line between d1 and d2 along the axis representing position)

Displacment is a ___quantity because

vector, because in addition to magnitude, it has direction.

The magnitude of displacement is known as

distance

When the displacement between two points of time (t1 and t2) is positive, that means

its magnitude is measured in the positive direction

When the displacement between two points of time (t1 and t2) is negative, that means

the displacement is negative, and its magnitude is measured in the negative direction

Elapsed time can be given by the relationship

t=t1-t2

Average Velocity=

(slope) d/t (measured in units such as meters per second (m/s), or miles per hour (mph))

What does average velocity indicate?

how rapidly the position of the object (d) has changed over the time interval (t)

What type of quantity is velocity?

A vector quantity, because it has both magnitude and direction

What is the magnitude of velocity?

Speed

With velocity, we can use positive and negative signs to represent:

motion in opposite directions

Instantaneous Velocity

the slope of a line drawn tangent to the graph at that point

The slope of the velocity-time graph is given by the relationship

Δv/t

What does Δv/t represent?

acceleration, measured in units like meters/seconds^2 (m/s^2)

When the slope of a velocity-time graph is straight,

the acceleration in this case is constant or uniform.

Equation to find the uniform acceleration of a velocity-time graph

a=Δv/t

Acceleration is a ____quantity because

vector, because it has both magnitude and direction.

A positive acceleration means that

the velocity of an object is becoming more positive with time

A negative acceleration means that

the velocity of the object is becoming more negative with time.

Positive displacement

the object traveled the distance in the positive direction

How to calculate displacement:

Find the area underneath the line in a velocity-time graph. (add the difference displacements for all sections underneath the graph)