The graph represents the simple harmonic motion of a pendulum. A graph with displacement on the y axis and time on the x axis. There is a transverse wave form drawn from the y axis toward the right with the x axis at the equilibrium position of the wave. The top of the first crest os labeled A. The distance from the first trough to the second trough is labeled C. The height of the second crest is labeled B. The distance from the top of the crest to the bottom of the trough is labeled D. Which arrow indicates the period of the motion? A B C D

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?