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course Phy 121

The problem:A ball starts with velocity 4 cm/sec and ends with a velocity of 10 cm/sec.

What is your best guess about the ball's average velocity?

answer/question/discussion (start in the next line):

10cm/sec + 4cm/sec =14cm/sec

(14cm/sec )/2 =7cm/sec

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Without further information, why is this just a guess?

answer/question/discussion (start in the next line):

Because there is no way to know if the the ball was accelerating at a constant rate through out.

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If it takes 3 seconds to get from the first velocity to the second, then what is your best guess about how far it traveled during that time?

answer/question/discussion (start in the next line):

(7cm/sec)*3sec=21cm

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At what average rate did its velocity change with respect to clock time during this interval?

answer/question/discussion (start in the next line):

(10cm/sec)- (4cm/sec)=6cm/sec

(3sec)-(0sec)= 3sec

(6cm/sec)/(3sec)=6cm/3sec^2"