1) A rock is suspended form a scale reads 10.0 N. A beaker of water is raised up so the rock is totally submerged in the water. The scale now reads 6.25 N. What is the density of the rock? ((answer: 2.67 times the density of water))
2) A sewing machine needle moves up and down in simple harmonic motion with an amplitude of 1.27 cm and a frequency of 2.55 Hz. What is the maximum speed of the needle? ((answer: 20.3 cm/s))