If force and displacement are in opposite directions, will work be positive or negative?

By what primary heat transfer mechanism does the sun warm the earth?

In this lab you will use a cart and track to explore various aspects of motion. you will measure and record the time it takes the cart to travel certain distances, and then complete some calculations. in the space below, write a scientific question that you will answer by doing this experiment.

The safe load, l, of a wooden beam of width w, height h, and length l, supported at both ends, varies directly as the product of the width and the square of the height, and inversely as the length. a wooden beam 4 inches wide, 9 inches high, and 240 inches long can hold a load of 6810 pounds. what load would a beam 3 inches wide, 8 inches high, and 144 inches long, of the same material, support? (round off your answer to the nearest integer.)