Achild bounces a 57 g superball on the sidewalk. the velocity change of the superball is from 26 m/s downward to 16 m/s upward. if the contact time with the sidewalk is 1 800 s, what is the magnitude of the average force exerted on the superball by the sidewalk? 1. 2183 n 2. 2107 n 3. 1992 n 4. 1877 n 5. 2068 n 6. 1839 n 7. 2030 n 8. 1954 n 9. 2145 n 10. 1915 n

Diego is trying to lift a piano to the second floor of his house. diego uses a pulley system and gives a big lift to the piano. the piano moves upward, then stops, and then it starts to fall to the ground. which list best describes the forces on the piano in the proper order? a.positive force, balanced force, negative force b.negative force, balanced force, positive force c.positive force, unbalanced force, negative force d. negative force, unbalanced force, positive force