You drop 12 balls off of a platform that is an unknown distance above the ground and measure the time it takes for the ball to fall to the ground. how far above the ground is the platform? give a range for this answer that you can be 95% sure that the true distance lies within. assume that g = 9.80 m/s2. all times are given in seconds.

The space between two 15-in.-long concentric cylinders is filled with glycerin (viscosity = 8.5 × 10-3 lb·s/ft2). the inner cylinder has a radius of 1 in. and the gap width between cylinders is 0.1 in. determine (a) the torque and (b) the power required to rotate the inner cylinder at 180 rev/min. the outer cylinder is fixed. assume the velocity distribution in the gap to be linear.