Why is the velocity of a wave in shallow water proportional to depth of water

Acar tire contains 0.0380 m^3 3 of air at a pressure of 2.20 ×10^{5} 5 n/m^2 2 (about 32 psi). how much more internal energy does this gas have than the same volume has at normal atmospheric pressure, 1.01x10^5 5 pa?

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?