Which of the following is an example of an opposing force? A. Gravity pulling a ball down a hill
B. Wind blowing a leaf off of a tree
C. Gravity holding a rock still on the ground
D. Water pushing against someone as they wade through a pool

What is the average speed of a car that travels 40 mph for 1 hour and 60 mph in another hour?

Asap and show ! a 14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.

Global warming will produce rising sea levels partly due to melting ice caps but also due to the expansion of water as average ocean temperatures rise. to get some idea of the size of this effect, calculate the change in length of a column of water 1.00 km high for a temperature increase of 1.00ºc. note that this calculation is only approximate because ocean warming is not uniform with depth. (answer in ×10^{-3} −3 m)