Q1. When a 0.5 kg mass is suspended from a spring, the spring stretches 4 cm. The mass is then displaced 2 cm from its equilibrium position and released. a) What is the spring constant? b) What is the mechanical energy of the mass? c) What is the speed of the mass as it passes through its equilibrium position going down and going up?
Q2. The power output of a cyclist moving at a constant speed of 6.0 m/s on a level road is 120 W. a) What is the frictional force exerted by her (and the bicycle) by the air? b) By bending low over the handlebars, the cyclist reduces the wind resistance by 18N. If she maintains her former power output, what will her speed be?
Q3. A girl throws a 0.2 kg ball a distance of 6 m straight up in the air (assume no air resistance). a) What is the kinetic energy of the ball as it leaves the girl's hand? b) How much work does the girl do in throwing the ball? c)If the girl's arm muscle contracted a distance of 0.050 m while throwing the ball, what was the average force exerted by the muscle.