Q1. A straight 2.60 m rod pivots around a perpendicular axis so that it can swing freely in a horizontal plane. Jane pushes perpendicular to the rod at its midpoint with 98.0 N of force, directed horizontally, to make a torque. Matt has attached a rope to the end of the rod, and is pulling on it horizontally to create an opposing torque. The rope creates a 67.0° angle with the rod. With what force must Matt pull so that the net torque on the rod is zero?

Q2. The wavelength of the laser beam used in a compact disc player is 790 nm. Suppose that a diffraction grating produces first-order tracking beams 1.2 mm apart at a distance of 3.o mm from the grating. Approximation the spacing between the slits of the grating.

Q3. A 310 piano slides 3.5 down a 30 incline and is kept from accelerating by a man who is pushing back on it parallel to the incline. The effectual coefficient of kinetic friction is 0.37. Compute the work done by the man on the piano.