course PHY 231
7/6 23:40
What are the acceleration and final velocity of an object whose average velocity, accelerating uniformly from rest for 7.9 seconds, is 59 cm/s? How far does the object travel during the 7.9 seconds?
Know:
V_i = 0
V_avg = 59cm/sec
Want:
V_f
A_avg
'ds
Solution:
V_f = 2*V_avg = 2*59cm/sec = 118cm/sec
A_avg = 'dV/'dt = (118cm/sec) / 7.9sec = 118cm/7.9sec^2 = 14.93cm/sec^2 = 14.9cm/sec^2
'ds = v_avg*'dt = (118cm/sec) * 7.9sec = 932.2cm = 932cm"
Good. Remember that V_f = 2*V_avg holds if acceleration is uniform and initial velocity is zero. Otherwise it's usually not so.
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