course phy201
7:23 2/10/10
Randomized problem 3 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?
average velocity = 59 cm/s
time = 7.9 seconds
acceleration = change of velocity / change in clocktime
acceleration = 59cm/s / 7.9 seconds = 7.5 cm/s^2
Change in velocity is not the same as average velocity.
Average velocity is not used in the calculation of change in velocity.
Average velocity can often, as in this case, be used in the calculation of final velocity.
However change in velocity is directly related to initial and final velocities, not to average velocity.
Final velocity = 2* 59cm/s = 118 cm/s (since the final velocity is the average velocity * 2)
right, since initial vel is zero and accel is uniform
The final velocity should have been used in calculating your change in velocity.
'ds= ' vave * 'dt
'ds = 59 cm/s * 7.9 s = 466.1 cm