A student removed a wool hat from her head. Her hair stood up from static electricity. What did her hat do to cause this

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?

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)

Avertical clean glass piezometer tube has an inside diameter of d = 1 mm and is used to measure pressure in a horizontal pipe carrying water as shown. due to pressure in the pipe, the water at 20c rises into the tube to a height h. if the water pressure in the pipe is p = 500 pa gauge, estimate the height h: (a) without considering surface tension (b) with surface tension (capillary) effects. the contact angle  can be assumed at 30 deg