18. In the diagram below, when the system is being pulled to the right, the greatest tension is and the least is T, 19. For two given surfaces in contact with one another, the coefficient of kinetic friction is generally than the corresponding coefficient of static friction. 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 greatest is The position of the stone when the tension in the string is the least is 20. 21. For a planet orbiting the Sun, the centripetal force is supplied by 22. If Earth\'s radius and mass were both twice their present values, the acceleration due to gravity at Earth\'s 23. m/s surface would have a value of proportional to the distance the spring moves from equilibrium. The change in momentum of an object is called the law states that the magnitude of the force exerted by an ideal spring is directly 24. A ball is dropped and bounces back to 90% 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 One charge freely moves away from another charge. The force between the two charges changes while the total energy is 26. 27. 28. The bending of a wave due to changing speed is called 29. Energy radiates from an atom in bundles called 30. A decay that involves a high speed electron is a(n) 31, The time required to reduce radioactivity by 50% is the decay. Solution 18) Greatest is T3 least is T1 19)coefficient of kinetic friction is generally less than coefficient of static friction 20)Tension in the string is highest when the stone is lowest tension in string is lowest when the stone is highest 21)Gravitational force .