course PHY 231
7/13 2314
Reason out the quantities v0, vf, Dv, vAve, a, Ds and Dt: If an object’s initial velocity is 10 cm/s, and it accelerates uniformly through 36 cm in 3 seconds, then what is its final velocity?
Known:
v0 = 10cm/s
'ds = 36cm
'dt = 3s
Inferred:
v_avg = 12cm/s
2v_avg - v0 = vf = 14cm/s
'dv = 4cm/s
a = 1.3cm/s^2
Using the equations which govern uniformly accelerated motion determine vf, v0, a, Ds and Dt for an object which accelerates through a distance of 36 cm, ending with
velocity 10 cm/s and accelerating at 1.333 cm/s/s.
'ds = 36cm
vf = 10cm/s
a = 1.333cm/s^2
vf^2 = v0^2 + 2 a `ds
100cm^2/s^2 = v0^2 + 95.976cm^2/s^2
v0 = sqrt(4.024(cm/2)^2) = +-2.00
Positive:
v0 = 2cm/s
'dv = 8cm/s
v_avg = 6cm/s
'dt = 6s
Negative:
v0 = -2cm/s
'dv = 12cm/s
v_avg = 4cm/s
'dt = 9s"
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