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course Phy 201
9/24 3
Reason out the quantities v0, vf, v, vAve, a, s and t: If an object’s velocity changes at a uniform rate from 9 cm/s to 12 cm/s as it travels 84 cm, then what is the average acceleration of the object?
Using the equations which govern uniformly accelerated motion determine vf, v0, a, s and t for an object which accelerates through a distance of 84 cm, starting from velocity 9 cm/s and accelerating at .375 cm/s/s.
vo=9cm/sec
vf=12cm/sec
‘ds=84cm
a_Ave=?
‘ds = ((v0 + vf)/2) * ‘dt
84cm = ((9cm/sec + 12cm/sec)/2) * ‘dt
164cm = 21cm/sec * ‘dt
8sec = ‘dt
a_Ave = (vf-v0)/’dt
a_Ave = (12cm/sec – 9cm/sec)/8sec
a_Ave = 3/8 cm/sec^2
a_Ave = .375 or .4 (if rounding to significant figures)
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