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course Phy 121
9/18 9:10pm
Determine the acceleration of an object whose velocity is initially 18 cm/s and which accelerates uniformly through a distance of 55 cm in 4.2 seconds.
We can reason this one out. The vAve is 55cm/4.2 = approx 13cm/s. Since the vAve is( v0+vf)/2 , vf + v0 = 26cm/s, vf= 26cm/s -18cm/s = 8cm/s.
aAve = `dv/`dt
aAve = (vf-v0) /`4.2 s
aAve = (8cm/s - 18cm/s)/4.2s
aAve = (-10cm/s)/4.2s
aAve = -2.4cm/s^2 approx.
This makes sense that the velocity would be decreasing. At 18cm/s if the velocity were held constant or increasing, it would cover 55cm in less than 4.2 seconds.
&#This looks very good. Let me know if you have any questions. &#