Hold your index finger and middle fingers close to each other, leaving a small slit between them about 1 mm in width. Look through the slit into a source of light such as the window or lamp (NOT THE SUN). You will need to look with one eye up close to the slit. Why do the vertical black lines show up when your fingers are close together but not when they are far apart? Explain.

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 11.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.80 m/s; (b) he is then lifted at the constant speed of 4.80 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 78.0 kg rescue by the force lifting him during each stage

The slope of a velocity time graph over any interval of time gives the during that interval

What’s #16 asking me and how do i solve it?