3B Scientific Friction Measuring Apparatus - Manual (Page 3)

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Fig. 2: Investigation of static and sliding friction with
friction body B with different weights (left) and
different materials constituting the contact sur-
face, in that a different surface coating is glued
to the sliders (right)
6. Measurements conducted when the fric-
tion plane is at an incline
The friction track can be inclined by an angle
ϕ from the normal. As a result, the normal force
F
N
exerted by a weight G changes according to
the equation: ϕ ⋅ = cos
N
G F .
• Align the friction surface so that the pointer
of the protractor is set to the desired inclina-
tion (0 – 60°).
• Insert the sliding friction surface into the
friction track either with its smooth or coarse
facing down.
• Place friction body C onto the sliding friction
surface so that the castors on the narrow
side face downwards towards the track wall
(see Fig. 3).
6.1 Static friction
• Pull the sliding friction surface, making sure
it is displaced with a uniform motion.
• Read the maximum value from the dyna-
mometer while the friction body is still being
dragged along with the sliding friction sur-
face.
• Perform this measurement on several occa-
sions and calculate the average.
This value represents a measure of the static
frictional force.
6.2 Sliding friction
• Conduct measurements as described under
6.1. However, take the reading on the dy-
namometer as soon as the friction body has
stopped moving along with the sliding fric-
tion surface.
• Perform this measurement on several occa-
sions and calculate the average.
This value represents a measure of the sliding
frictional force.
Fig. 3: Measurements conducted with friction body C
when the friction track is inclined