When earth receives energy from the sun,
a. some energy is reflected back into space
b. some is absorbed by the atmosphere
c. some is absorbed by land and water on earth's surface
d. all of the above

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?

The earth exerts a gravitational force of 500 n on amy. what is amy’s mass in kg?

What practical value did astronomy offer to ancient civilizations?