MOTION:
VELOCITY AND ACCELERATION TICKER-TIMER
EXPERIMENT TASK
1AIM:
This activity is about velocity, acceleration, and deceleration,as
influenced by forces of friction and gravitation.
And you will be introduced
to a device called a ticker-timer. At
the end of the activity, the learner should be able to: - Describe
how friction compensation happens on a runway.
- Describe
how a ticker-timer works.
- Describe
the experimental procedures to measure the velocity of a trolley.
- Identify
ticker-timer tapes that show uniform velocity and those that show accelerated
motion.
- Calculate
velocity from a ticker tape.
- Determine
acceleration due to gravity using a ticker-timer.
APPARATUS: To
set up this activity, the following equipment is needed: Trolleys, runways, ticker-timers,
ticker tapes, and rulers. PROCEDURES:
- Set up the trolley
to move on a horizontal runaway as shown in figure below (under the guidance of
your teacher). A ticker tape passing through the ticker timer is attached to the
trolley.
- Observe
and describe how the trolley moves along the runaway.
- Suggest
how the trolley can be made to moves down the runway at a constant speed.
- Ask
your teacher to help you produce various tapes for constant velocity and accelerated
motion.
- Examine
the various tapes obtained
- Describe the various
tapes that show uniform velocity and those showing accelerated motion.
| Tape
(take initial part of the tape to be on the left) | Describe
in each case how spacing between dots varies | Describe
the type of motion represented | A | 
| | |
B | 
| | |
C | 
| | |
D | 
| | |
E | 
| | |
TASK
2 DETERMINING
VELOCITY FROM THE TICKER TAPE
Answer the
following questions: - If
the frequency of the ticker timer is f, what is the time interval between
two successive dots?.
- If
frequency of the ticker timer is 50Hz, what is the time interval for the following
cases:
- From
the 1st to the 2nd dot;
- From
the 1st to the 5th dot;
- From
the 1st to the 100th dot;
The
following examples show various tapes each of length 8cm obtained using a ticker
timer of frequency 50Hz.
In each case find the time interval of the tape and
the velocity in ms-1.
| Tape | Time
interval | Velocity
| A | 
| | |
B |
| | |
C |
| | |
| | | |
TASK
3 DETERMINING
ACCELERATION FROM THE TICKER TAPE - Set
up the experiment and produce a number of ticker tapes using a trolley running
on an inclined runway.
- Discuss
how to choose the interval for the initial and final velocities on the accelerated
tape.
- Discuss
why the initial dots could be ignored (cut off).
- Calculate
initial and final velocities on the accelerated tapes.
- Discuss
how to obtain the time taken to change from initial to final velocity.
- Calculate
acceleration on the accelerated tapes.
Calculate
acceleration for the tapes below, in the steps given. Take frequency f = 50Hz
| |
| A | 
The
distance x = 18cm
The distance y = 30cm | Time
for initial interval x or final interval y, t/s | |
Initial
velocity, u/ms-1 | |
Final
velocity, v/ms-1 | |
Time
to change from average velocity u to average velocity v, T/s | |
Acceleration,
a | |
B | 
The distance x = 14cm
The distance y = 24cm
| Time,
t | |
Initial
velocity, u | |
Final
velocity, v | |
Time,
T | |
Acceleration,
a | |
TASK
4 DETERMINING
ACCELERATION DUE TO GRAVITY USING THE TICKER TIMER - Discuss
the set up of the experiment.
- Set
up the experiment as shown in diagram and produce a number of ticker tapes.
- Use
the method of finding acceleration (from above) to determine the acceleration
due to gravity.
|
| Time
for initial interval x or final interval y, t/s | |
Initial
velocity, u | |
Final
velocity, v | |
Time
to change from average velocity u to average velocity v, T/s | |
Acceleration,
a | |
Review
your understanding ITEM
1
| Tape
| Describe
in each case how spacing between dots varies | Describe
the type of motion represented | A | 
| | |
B | 
| | |
C | 
| | |
D | 
| | |
E | 
| | |
ITEM
2 The
following examples show various tapes each of length 8cm got using a ticker timer
of frequency 50Hz.
In each case find the time interval and the time interval
of the tape and the velocity in ms-1.
| Tape | Time
interval | Velocity
| A |
| | |
B |
| | |
C |
| | |
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Useful
web links
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