This is another question about the article in the October 20…

This is another question about the article in the October 2018 issue that referred to a study claiming that two-thirds of all portable internet devices in the United States end up in a landfill when they are replaced.   QUESTION: Is this number (two-thirds) a parameter or a statistic?

A solid concrete cylinder (r = 2400 kg/m3) with a diameter o…

A solid concrete cylinder (r = 2400 kg/m3) with a diameter of 80.0 cm and a height of 15.0 cm is spinning on a frictionless pivot with an initial rotational velocity of 2.00 RPM (revolutions per minute). You want to stop the cylinder by pressing against the outer edge with a wooden stick, where the coefficient of static friction between the stick and the concrete is 0.750 and the coefficient of kinetic friction is 0.600. If you want to stop the cylinder in exactly 30.0 seconds, with what force must you press the stick against the edge of the cylinder? Recall the moment of inertia of a solid cylinder is ½ MR2.