Sally and maria hypothesized that earthworms lived only in dark, damp places. they measured a one-meter square in a shady spot near a stream. they dug through the soil and collected earthworms. they collected 43 worms. they repeated the experiment in several locations, sunny and dry included. they found the most worms in the shady, damp plot near the stream. several other groups of science students carried out the same experiment and got similar results. this is an example of a) bias. b) repetition. c) replication. d) validity.

If an inclined plane is 5 m long and 2 m high, what is its mechanical advantage? a. 2.5 b. 3 c. 7 d. 10

Part f - example: finding two forces (part i) two dimensional dynamics often involves solving for two unknown quantities in two separate equations describing the total force. the block in (figure 1) has a mass m=10kg and is being pulled by a force f on a table with coefficient of static friction îľs=0.3. four forces act on it: the applied force f (directed î¸=30â above the horizontal). the force of gravity fg=mg (directly down, where g=9.8m/s2). the normal force n (directly up). the force of static friction fs (directly left, opposing any potential motion). if we want to find the size of the force necessary to just barely overcome static friction (in which case fs=îľsn), we use the condition that the sum of the forces in both directions must be 0. using some basic trigonometry, we can write this condition out for the forces in both the horizontal and vertical directions, respectively, as: fcosî¸â’îľsn=0 fsinî¸+nâ’mg=0 in order to find the magnitude of force f, we have to solve a system of two equations with both f and the normal force n unknown. use the methods we have learned to find an expression for f in terms of m, g, î¸, and îľs (no n).

Aball has an initial velocity of 3 m/s. if there is no friction, what is the highest it could roll?