EVIDENCE 3
Name
Class
Date
Experiment Report
Theme
Title
Aim
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:
:
:
2 Al-Zahrawi
26 June 2012
Activity 7.1
: Force and motion
: How different types of surface affect frictional force
: To show that different types of surface affect the magnitude of
frictional force.
Problem statement
:
How do different types of surface affect the magnitude of frictional force ?
Apparatus and materials :
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Spring balance
Tray
Wooden block
Sand paper
Waxed paper
Writing paper
Pencils
Glass rods
Oil
Beads or beans
Hypothesis : The rougher the surface, the higher the magnitude of frictional
force
Variables
:
That keep constant
That is manipulated
That responds
: Type of wooden block
: Type of surface
: The magnitude of frictional force
1
Procedure :
1. A wooden block is placed with its wider surface on a wooden table top.
2. A spring balance is hooked onto the wooden block and pulled until the
wooden block move.
3. Just before the wooden block moves, the reading on the spring balance is
recorded.
4. The experiment is repeated by :
a) Pulling the wooden on a piece of smooth glass.
b) Pulling the wooden block on a piece of sand paper.
c) Placing the wooden with its smaller surface on the table and then
pulled.
d) Placing another wooden block on the first wooden block and then
pulled.
A
B
Sand paper
2
C
pencils
D
oil
E
Beads or beans
Analysis :
The spring balance reading equals to the frictional force acting between the
wooden block and the surface in contact.
Conclusion :
The rougher the surface between them in contact, the greater the frictional force.
3
Questions !
1. Do different types of surfaces affect the magnitude of frictional force?
Yes
2. Do rough surface have more friction than smooth ones?
Yes
3. Based on the observations , state different in friction by wooden block on
the table and on the sand paper.
The magnitude of frictional force on the table is less than the sand paper.
4. What inferences can be make based on the observations?
The magnitude of frictional force on the oil is the less than others because
its surface is smooth.
5. State the relationship between type of contact surface and the frictional
force?
The smoother the type of contact surface, the less the frictional force.
6. Based on observation, arrange the roughess surface in contact in
ascending order.
Oil, glass rod, beads, or beans , table, sand paper.
7. State the operational definition of frictional force.
Frictional force is shown by reading of spring balance.
Result of the experiment
Type of surface
Oil
Sand paper
Table
Pencils or glass rod
Beads or beans
Magnitude of frictional force (N)
0.2
1.1
0.5
0.3
0.3
4