¬
Draw and use
motion diagrams to describe motion

¬
Use particle
model to represent moving objects

¬
Differentiate
between vector and scalar quantities

¬
Define
displacement and distance and compare and contrast them

*1.
**Homework check and discuss. *

*2.
**Motion
Diagrams*

Use
lab activity A1 to introduce the concept of motion diagrams.

Students
will draw motion diagrams for a lab cart under the following conditions:

i.
traveling
uniformly to the right

ii.
traveling
uniformly to the left

iii.
traveling uphill

iv.
traveling
downhill

-arbitrarily chose a time interval (i.e. 1/10 s)

Discuss
the shape of the motion diagrams for each condition.

Easier
to represent the motion with ÒdotsÓ (particle model)

Ex. represents
an object slowing down over time

*3.
**Position of
an object*

Like
other measurements, position is measured relative to a starting point or
reference.

The
origin is the point at which the variables have the value of zero.

Place
a mark of Ò0Ó on the board and label it origin.

Mark
a position (A) 1.0 m to the left and another (B)1.0 m
to the right of the origin.

A
0
B

How
are these positions the same? (same distance from 0)

How
are they different? (different direction)

How
can we distinguish? (A
–1.0 m, B +1.0 m)

How
far are A and B apart? (2.0
m)

Does
this require any further information (i.e. direction)? (No)

*Distance* is the measured separation between two positions.

Ex.
the distance between Doha and Dukhan is 80 km

LetÕs
move from A to B. Is this the same as moving from B to A? (No)

The
change in position from A to B is 2.0 m to the right or +2.0 m

The
change in position from B to A is 2.0 m to the left or –2.0 m

*Displacement* defines the distance and direction between two
positions.

Ex.
The displacement of Dukhan is 80 km __west__ of
Doha

This
can calculated using delta notation (D– change in)

Dd = d_{f}_{
}- d_{I}_{ } Dd = d_{B} – d_{A}
= +1.0 m – (-1.0 m) = +2.0 m

Some
descriptions require a direction!

*4.
**Vector and
Scalar Quantities*

A *vector* quantity is represented by both a
magnitude (amount) and a direction.

Ex.
displacement 80 km [E], 12 cm up; velocity -14.5 m/s, force pull down with 15 Newtons

A *scalar* quantity is represented by a
magnitude only. Ex. distance, speed, mass, time, temp.

5. Assign Exercise A1
(handout) Ch 2: #5 – 7, 35, 37, 38, 49, 51, 53