This is the pond behind Serge's house. There are lots of catfish swimming in this pond. Trees ring the pond and rushes and irises live at the pond's edge. The bottom of the pond is sandy and Serge likes to pick up flat rocks from the shallow water and skim them across the top of the water. This summer, Serge has seen lots of dragon flies and mosquitoes at the pond also. All the catfish that live in the pond behind Serge's house make up a of catfish.

a. community
b. family
c. habitat
d. population

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?