24. A 78 g steel ball is released from rest and falls vertically onto a rigid surface. The ball strikes the surface and is in contact with it for 0.5 ms. The ball rebounds elastically, and returns to its original height
during a round trip of 4 s. Assume that the surface does not deform during contact. What is the
maximum elastic energy stored by the ball? (Use acceleration due to gravity g = 10 m/s2)
A. 23.1)
B. 43)
C. 11.5 J
D. 15.6)

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?

The two stars in a certain binary star system move in circular orbits. the first star, alpha, has an orbital speed of 36 km/s. the second star, beta, has an orbital speed of 12 km/s. the orbital period is 137 d. a) what is the mass of the star alpha? b) what is the mass of the star beta?

Increasing the pressure on one spot of a fluid will increase the pressure everywhere else in the fluid a. pascals principal b. archimedes' principal c. bernoulli's principal