Phys 100
Spring 2009
Concepts of Physics: Class Exercise 1
1 Speed and Velocity
Various balls move along a straight horizontal path as illustrated. Photographs of the balls
at intervals spaced 1 s apart are provided.
1 s 2 s 3 s 4 s 5 s Ball A
1 s 2 s 3 s 4 s 5 s
Ball B
5 s 4 s 3 s 2 s 1 s Ball C
1 s 2 s 3 s Ball D
a) Rank the balls in order of increasing speed.
b) Which, if any, of the balls have the same velocity?
2 Velocity and Acceleration
In which of the following cases is the acceleration of the object described exactly zero?
a) A bullet that travels perfectly horizontally with a speed of 200 m/s?
b) A ball which swings around in a circle at constant speed.
c) A piece of gum which is thrown at a wall and sticks to the wall.
d) A ball that is dropped to the floor.
e) A ball that is thrown upward.
Provide an example of the motion of an everyday object and determine whether the acceler-
ation of the object is exactly zero or not.
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