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course Phy 201
10/3 12
A ball starting from rest rolls 11 cm down an incline on which its acceleration is 27 cm/s2, then onto a second incline 44 cm long on which its acceleration is 9 cm/s2. How much time does it spend on each incline?v0=0
vf=?
‘ds= 11cm
a= 27cm/sec^2
vf^2 = v0^2 + 2a * ‘ds
vf^2 = 0 + 2(27cm/sec^2) * 11cm
vf=24.4cm/sec
vAve = (vf + v0)/2
vAve = (24.4cm/sec + 0)/2
vAve = 12.2cm/sec
‘ds = vAve * ‘dt
11cm = 12.2cm/sec * ‘dt
‘dt = .9sec (this is the 1st ramp)
v0=24.4cm/sec
a = 9cm/sec^2
‘ds= 44cm
vf^2 = v0^2 + 2a * ‘ds
vf^2 = 24.4cm/sec + 2(9cm/sec^2) * 44cm
vf = 37.3cm/sec
vAve = (vf + v0)/2
vAve = (24.4cm/sec + 37.3cm/sec)/2
vAve = 30.9cm/sec
ds = vAve * ‘dt
44cm = 30.9cm/sec * ‘dt
‘dt = 1.4sec (this is the 2nd ramp)
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