Students in a high school physics class
tested their hypothesis that the surface texture of a
block would affect its slide time (the time it took the
block to slide one meter down a smooth inclined
plane). See Figure 1.
Three identical wooden blocks were used in two
different experiments. The surface of the first block
was left uncovered; the surface of the second block
was covered with fine sandpaper; and the surface of
the third block was covered with felt. The angle of
inclination was 45° in both experiments.
Experiment 1
The students measured the slide time of
each block when the block started its downward
slide from rest (an initial velocity of zero). The
results are shown in Table 1.
Table 1
Block Slide Time (sec)
uncovered 2.2
sandpaper 2.8
felt 2.0
Experiment 2
The students measured the slide time of
each block after the block had slid, from rest, three
quarters of a meter down the incline. Thus, when
slide time was measured, each block had an initial
velocity that was greater than zero. See Figure 2.
The results are shown in Table 2.
Table 2
Block Slide Time (sec)
uncovered 1.1
sandpaper 2.0
felt 0.8
According to Experiment 1, when compared to
the slide time of the uncovered block, the slide
times of the sandpaper and felt covered blocks
were:
A.
both higher.
B.
both lower.
C.
higher for one and lower for the other.
D.
identical.