Revised 91

course PHY 121

A ball accelerates uniformly as it rolls 20 cm down a ramp, starting from rest, in 2 seconds. •What are its average velocity, final velocity and acceleration?

20cm / 2s = 10cm/s

10cm/s * 2 = 20cm/s

20cm/s – 10cm/s =10cm/s / 2s =5cm/s

###This should be 10cm/s * 2 = 20cm/s

###20cm/s / 2s = 10cm/s^2

answer/question/discussion:

• If the time interval is in error so that it is 3% longer than the actual time interval, then what are the actual values of the final velocity and acceleration?

2s * 3% = 0.06

20cm/s – 0.06=19.94cm/s

5cm/s – 0.06=4.94cm/s

###This should be 20cm/s / 2.06s = 9.7cm/s

###9.7cm/s * 2 =19.4

### 19.4cm/s / 2.06s =9.4

###.6cm/s^2 / 10cm/s^2=.06

answer/question/discussion:

• What is the percent error in each?

0.06

###This should be 3% as well as the final 6%

"

&#Good work. Let me know if you have questions. &#