Astronauts in space "weigh" themselves by oscillating on a spring. suppose the position of an oscillating 72kg astronaut is given by x=(0.26m)sin((Πrad/s)·t), where t is in s.
What force does the spring exert on the astronaut at t = 1.0s (note that the angle of the sine function is in radians)?
What force does the spring exert on the astronaut at t=1.5 s?