Chapter 2 Describing Motion: Kinematics in One Dimension

Answer sheet

1a. During aerobic exercise, people often suffer injuries to knees and other joints due to high accelerations.  When do those high accelerations occur?

1b. Estimate the acceleration you subject yourself to if you walk into a brick wall at a normal walking speed.  (Make a reasonable estimate of your speed and of the time it takes you to come to a stop, and explain those numbers also.)

1c. The figure shows a displacement (in meters--the units got cut off) vs. time graph for a ball rolling along the floor.  What was the speed of the ball during the third second?

a. 1 m/s

b. 2 m/s

c. 3 m/s

d. It cannot be determined from the graph.

1d. Are there any thoughts you wish to share, whether they are about this assignment, the reading (what seems impossible, what makes no sense, what you'd like to spend time on in class, what you really found interesting etc) or the course?

2a. A man drops a baseball from the edge of a roof on a building.  At exactly the same time, another man throws a baseball vertically up toward the man on the roof in such a way that the ball just barely reaches the roof.  Does the ball from the roof reach the ground before the ball from the ground reaches the roof, or is it the other way around?

2b. Is it possible for an object's instantaneous velocity and instantaneous acceleration to be of opposite sign at some instant of time?  Explain your answer.

2c. A ball is thrown downward (not dropped) from the top of a tower.  After being released, its downward acceleration will be

a. greater than g.

b. exactly g.

c. smaller than g.

d. not covered in the reading assignment.

2d. Are there any thoughts you wish to share, whether they are about this assignment, the reading (what seems impossible, what makes no sense, what you'd like to spend time on in class, what you really found interesting etc) or the course?