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Lab 2
Investigating Distance and Speed; Displacement and Velocity
Introduction
:
This investigation is designed to help you learn about distance and speed,
and distinguish it from displacement and velocity.
Distance is the length of the path traveled by an object. Speed depends on
how fast the distance is covered.
Distance covered
∆
x
Average speed =
=
Time taken
∆
t
In this investigation you will be using a ticker timer and paper tape to
measure the speed of a trolley moving on a frictionless track. The ticker
timer ticks 40 times a second when set on high, producing 40 dots per
second on the paper tape that is moved through the timer. If you turn on the
ticker timer and run a length of paper through it, it will look like the diagram
below.
____________________________________________________________
… . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
____________________________________________________________
The distance between any two consecutive dots is the distance traveled in
1
0.025
40
s
=
Activity 1:
Cut about 1.0 m length of tape and slide one end of it into the timer. Turn the
timer on and pull it so that the entire tape runs through the timer. Cut off the
first few dots and then count 10 dots and cut off a length containing that 10
dots. Cut off at the 10th dot so that you have 10 intervals on the paper. Cut
off two more pieces that contains 10 intervals. Use your ruler to measure the
length of these strips on your computer screen.
Since you will be measuring the lengths on the computer screen, this
measured length needs to be converted to the actual length. In order to do
this, you need to obtain a
conversion factor
. I will give you the actual
length of one strip. Obtain your conversion factor as:
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View Full DocumentActual length
Conversion factor
Measured length
=
Actual length measured by the instructor = ……….
. m
The length of the strip measured on the computer screen = …………….m
Conversion factor = ………
Now use the conversion factor to obtain the actual lengths of each strip.
Length of strip 1 = …….
. m
Length of strip 2 = …….
. m
Length of strip 3 = …….
. m
QUESTION:
Why do you think it necessary to cut off the first few
dots?
………………………………………………………………………………
……………………………………………………………………………….
QUESTION:
If 40 dots are made in one second, what is the time taken
to mark 10 dots?. Record this time as
∆
t.
……………………………………………………………………………….
.
QUESTION:
If the length of strip 1 is L
1
, then the paper travels a
distance
∆
x = L
1
in time
∆
t. What is the speed of motion
of this strip?
……………………………………………………………………………….
QUESTION:
What is the speed of strip 2?
……………………………………………………………………………….
QUESTION:
What is the speed of motion of strip 3?
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 Fall '10
 George
 Physics

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