Nancy weighed her empty backpack with a spring scale. She found that the pack weighed 8.1 N. Suppose she picks up her backpack from a desktop and lifts it through
a height of 42 cm. How much gravitational potential energy does the backpack gain?
Show your work.

Which statement best describes how private industry decides where to spend the money on research and development

Mike walks 100 meter north, then walks 30 meters south. after this, he walks another 10 meters north. what is the magnitude of his total displacement during this walk,in meters?

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.