Two 2.0 kg bodies, a and b, collide. the velocities before the collision are
. after the collision,
. what are (a) the final velocity of b and (b) the change in the total kinetic energy (including sign)?
the first one is d hunted with stone-tipped spears
the second one is a
the angle near the y-axis is 60°, beause 90°-30°=60°. vy=10m/s*sin60°=8.66m/s
the conservation of energy always holds true even when not clearly observable in machines that are less than 100% efficient. more often than not a machine will suffer energy losses (e.g. consider for a cooling fan: friction between the rotating blades, drag resistance in the air the fan is pushing around, resistance in the wire, and heat radiating/conducting away from the circuitry).