17. In the diagram below, when the system is being pulled to the right, the least tension is and the greatest is T3 T2 4.\" 4? T2 E 18. For two given surfaces in contact with one another, the coefficient of static friction is generally than the corresponding coefcient of kinetic friction. 19. A rock is tied to the end of a string and whirled around in a circle that describes a vertical plane. The position of the stone when the tension in the string is the least is The position of the stone when the tension in the string is the greatest is 20. For a planet orbiting the Sun, the centripetal force is supplied by 21. If Earth's radius and mass were both three times their present values, the acceleration due to gravity at Earth's surface would have a value of m/sz. 22. The bending of a wave due to changing speed is called 23. is the internal friction between molecules caused by cohesive forces. 24. A ball is dropped and bounces back to 85% of its original height. The collision between the ball and the ground was 25. The force of attraction between all objects with mass is called 26. One charge freely moves away from another charge. The force between the two charges changes while the total energy is 27. law states that the magnitude of the force exerted by an ideal spring is directly proportional to the distance the spring moves from equilibrium. 28. The energy of a photon of light depends on the of light. 29. A decay that involves a helium nuclei is a(n) decay. 30. The time required to reduce radioactivity by 50% is the