A 135kg barrel is lifted vertically by a pulley system. It takes 23s to lift the barrel 11m. g = 9.8m/s^2. Calculate the Weight of the Barrel show your work.

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is

How much force was applied to an object if was moved 2 meters and the work done on the object was 8 joules? a. 0.25 n b. 4 n c. 6 n d. 16 n

The largest observatory complex in the world is on mauna kea, the tallest mountain on earth. what are some factors astronomers consider when selecting an observatory site? don’t forget practical ones. should astronomers, for example, consider building an observatory on denali (mount mckinley) or mount everest?