Problems concerning work may often involve a force that act as in a direction different from the direction of the motion of a body it is acting on. 20. During the fraction of a second that the two balls are in actual contact, each is slightly compressed. 21. The distance the object is from the lens is given by the following formula. 22. The way we represent numbers today has been evolving for thousands of years. 23. We may interpret the absolute value as being the number of units a given number is from the origin, regardless of direction. 24. The total energy of the spring at all times equals the 1/2 ks2 it was originally. 25. In the case of the Theory of Relativity, space and time are not the indiependent entities they were always believed to be. 26. The maximum potential difference there can be across the coil of the meter is 0.05V. 27. Maxwell's four equations summarize everything there is to know on electromagnetism. 12. Radian measure has enormous applications in mathematics and technology, some of which were indicated in the last four exercises of the previous section. 13. This vast field of science and engineering, only a part of which has been mentioned above, is usually called electronics. 14. Uranium consists of a mixture of two kinds of atoms, one of which is a little lighter than the other. 15. Scientists are concerned about why natural phenomena of which some often impress heavy calamities on man occur.