Which of the following describes an action-reaction pair? A. Your feet push down on the ground, and the ground pushes up on
your feet.
B. Your backpack pulls down on your shoulders, and your feet push
on the ground.
C. You push on a wall, and your feet push on the ground.
D. The Sun's gravity pulls on you, and Earth's gravity pulls on you.

3. on your graph, the data points between the black squares are data for elements with atomic numbers 3 through 9. locate these elements on your periodic table. what term or description would you use to identify these elements with respect to the periodic table?

This problem has been solved! see the answera non-uniform fire escape ladder is 6.0m long whenextended to the icy alley below. it is held at the top by africtionless pivot, and there is neglibible frictional force fromthe icy surface at the bottom. the ladder weighs 250n, and it'scenter of gravity is 2.0m along the ladder from the bottom. amother and child of total weight 750n are on the ladder 1.5m fromthe pivot. the ladder makes an angle θ with the horizontal.find the magnitude and direction ofa) the force exerted by the icy alley on the ladderb) the force exerted by the ladder on the pivotc) do your answers in part a and b depend on the angle?

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force