21. [-/3 Points] DETAILS OSCOLPHYS2016 6.2.WA.016. MY NOTES ASK YOUR TEACHER Consider a ball on a fixed-length string being whirled in a vertical circular path as shown in the diagram below. Use the direction rosette to answer the following questions. 8 C - 3 B 6 4 5 A 9 magnitude zero (a) When the ball is at location A, what is the direction of the Av vector? ---Select--- v (b) When the ball is at location B, what is the direction of the Av vector? ---Select--- v (c) When the ball is at location C, what is the direction of the Av vector? ---Select--- v22. [J2 Points] DETAILS OSCOLPHYSZME 7.1.P.001. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER How much work does a supermarket checkout attendant do on a can of soup he pushes 0.550 m horizontally with a force of4.9CI N? Express your answer in joules and kilocalor'ies. E J 1. Additional Materials ll] Reading 23. [J1 Points] DETAILS OSCOLPHYSZME 7.1.P.002. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A 32.0 kg person climbs stairs, gaining 3.?0 meters in height. Find the work done (in J} to accomplish this task. :1 1. 15. [-/2 Points] DETAILS OSCOLPHYS2016 5.1.WA.009. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) When rebuilding her car's engine, a physics major must exert 250 N of force to insert a dry steel piston into a steel cylinder at a constant velocity. What is the normal force in newtons between the piston and cylinder? (Assume the coefficient of kinetic friction is 0.3.) (b) What force (in N) would she have to exert if the steel parts are oiled, so that the coefficient of friction is 0.03? Additional Materials Reading Submit Answer 16. [-/1 Points] DETAILS OSCOLPHYS2016 5.1.WA.016. MY NOTES ASK YOUR TEACHER You promised your younger brother that you would give him a ride on his sled. You first pull him with a force F directed upward at an angle of 250 to the horizontal. After a while you decide to push him from behind with the same force F directed downward at an angle of 250. There is significant friction between the sled and the ice surface. Which of the following statements is true regarding the acceleration of the sled? O a pull = 2 push O apull > apush O apull apush O not enough information17. [-/3 Points] DETAILS OSCOLPHYS2016 6.1.P.004. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) What is the period of rotation of the Moon in seconds? (The period of rotation of the Moon in hours is 655.7 hr.) (b) What is the angular velocity (in rad/s) of the Moon? (Enter the magnitude.) rad/s (c) Given that the Moon has a radius of 1.7 x 100 m at its equator, what is the linear velocity (in m/s) at the Moon's surface? (Enter the magnitude of the linear velocity at the equator.) m/s Additional Materials Reading 18. [-/2 Points] DETAILS OSCOLPHYS2016 6.1.P.007. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A truck with 0.470 m radius tires travels at 21.0 m/s. What is the angular velocity of the rotating tires in radians per second? rad/s What is this in rev/min? rev/min19. [-/12 Points] DETAILS OSCOLPHYS2016 6.1.WA.001. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) Express the following angles in radians. 30 = rad 50 = rad 750 = rad 240' = rad (b) The following angles are in units of radians. Express them in degrees. 1/8 = 0.751 = 1.671 = 4TT = (c) The following angles are in units of radians. Express them in units of revolutions. 1/8 = rev 0.751 = rev 1.617 = rev 4TT = rev Additional Materials Reading20. [-/4 Points] DETAILS OSCOLPHYS2016 6.2.P.020. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER At takeoff a commercial jet has a 45.0 m/s speed. Its tires have a diameter of 0.700 m. (a) At how many rpm are the tires rotating? rpm (b) What is the centripetal acceleration at the edge of the tire? m/s2 (c) With what force must a determined 10 13 kg bacterium cling to the rim? N (d) Take the ratio of this force to the bacterium's weight. (force from part (c)/bacterium's weight) X Additional Materials Reading