746 rev/min * 1min /60 s = 12.43 rev/s = Vi
v = Vi - a t = 12.43 rev/s + a t
0 = 12.43 revs /s + a *(25 seconds)
a = -12.43 revs/s / 25 s = -0.497 revs/s^2
revs = Vi t + (1/2) a t^2 = 12.43*25 - 0.248*625 = 311 - 155 = 156 revs
or I could have used the average speed = 12.43/2 = 6.22 revs/s * 25s = 155 revs
since speed is linear in time with constant a
A friction welding machine is butt-welding two steel pipes together. Initially, the spinning pipe is rotating against the stationary pipe at a rate of frpm=746 rpm (rounds per minute). 25 seconds later the spinning pipe comes to rest and the molten steel between the two pipes begins to cool. Assuming that the deceleration of the moving pipe was uniform, how many revolutions did the moving pipe make before coming to rest?
1 answer
1 answer