A skier starting from rest skis straight down a slope 50 meters long in 5.0 seconds. What is the magnitude of the acceleration.

1 answer:

6 0

His average speed all the way is

   (50 meters) / (5 sec) = 10 m/s .

But, if the acceleration is uniform all the way down, then

Average speed = (1/2) (start speed + end speed)

Start speed = 0.
So
   Average speed = (1/2) (0 + end speed)

   = (1/2) of end speed .

   10 m/s = (1/2) of end speed

   End speed (at the bottom) = 20 m/s .

Magnitude of acceleration = (change in speed) / (time for the change)

      = (20 m/s) / (5 sec)

   =    4 m/s² .

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