1. When an object is experiencing "free fall," what is the only force acting upon it? 2. Does the acceleration of a falling object depend on its mass? Explain.

3. What is the rate of acceleration due to gravity on the earth?

4. In what direction does gravity always cause objects to accelerate?

5. If the initial velocity of an object is upward in the positive direction, what must the sign of the
acceleration due to gravity be in a calculation?

6. A ball is thrown straight up in the air.

a. At the peak of its ascent, what is it doing?
b. What is the ball's velocity at this point?

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).

Part a constants huck finn walks at a speed of 0.60 m/s across his raft (that is, he walks perpendicular to the raft's motion what is huck's velocity (speed and direction) relative to the river bank? express your answer to three significant figures and include the appropriate units. relative to the shore)

How is sound energy produced a. vibrating objects b. objects being heated c. temperature differences d. stationary objects