College Physics I 1401 057 Spring On Line Final 3 180 Minutes 200 Points Instructor Dr Ping Lu Student Name Grade Notes Please give me your all working on each question For instance 15 points A grocery bagger pushes a 2 00 kg bag of potatoes in such a way that the net external force on it is 65 0 N Calculate its acceleration Given m 2 00 kg F 65 0 N Find a Solve From the second law F ma so we have a F m 65 0 2 00 32 5 m s 2 Answer Its acceleration is 32 5 m s 2 All working on each question you should have four steps given find solve and answer 1 Multiple Choice total 80 points 1 State how many significant figures are proper in the results of the following calculation 106 7 90 46 210 1 01 a 1 b 2 c 3 d 4 A 2 State how many significant figures are proper in the results of the following calculation 5 9 2 a 1 b 2 c 3 d 4 B 3 What is the magnitude of the momentum of a 7000 kg truck whose speed is 20 m s Answer Given mass 7000 kg velocity 20 m s Find momentum Solve Momentum mass x velocity 7000 20 140000 kg m s Answer 140000 kg m s 4 How much work does a supermarket checkout attendant do on a can of soup he pushes 0 310 m horizontally with a force of 5 20 N Express your answer in joules and kilocalories Answer Given distance 0 310 m Force 5 20 N Find work Solve Work Fd 5 20N 0 310m 1 612 J Answer 1 612 J 5 The density of brass is 8 6 g cm3 What is this value in kilograms per cubic meter kg m Given D 8 6g cm3 Find D in kg m3 Solve 8 6g 1cm3 1 kg 1000g 100cm 1m 3 8600 kg m3 Answer 8600 kg m3 6 Assume that an MX missile goes from rest to a suborbital velocity of 6 0 km s in 40 0 s What is its average acceleration in m s 2 What is its average acceleration in multiples of g Given vo 0 km s vf 6 0 km s 6000 m s t 40 0s g 9 81 m s2 Find average acceleration Solve a v t 6000 40 150 m s2 Answer 150 m s2 Find average acceleration in multiples of g Solve 150 9 81 15 3 g m s2 Answer 15 3 g m s2 7 A stone is thrown horizontally from the top of a cliff One second after it has left you hand its vertical distance below the cliff is Given t 1 s a g 9 81 m s2 Find distance Solve Distance 1 2 at2 1 2 9 81 1 2 4 9 s 5 m Answer 5m 8 Compared to the mass of a certain object on earth the mass of the same object on the moon is a more b less c the same C 9 When the net force that acts on a hockey puck is 12 N the puck accelerates at a rate of 48 m s s Determine the mass of the puck Given Fnet 12 N a 48 m s s Find mass Solve F m a m F a m 12 48 0 25 kg Answer 0 25 kg 2 Questions total 120 points 1 10 points A grocery bagger pushes a 2 00 kg bag of potatoes in such a way that the net external force on it is 20 0 N Calculate its acceleration Given m 2 00 kg Fnet 20 0 N Find acceleration Solve F m a m F a m 20 2 10 0 m s2 Answer 10 0 m s2 2 15 points An ordinary workshop grindstone has a radius of 9 50 cm and rotates at 7000 0 rpm Calculate the centripetal acceleration at its edge in m s s and convert it to multiples of g Given r 0 095 m angular velocity 7000 0 rpm Find centripetal acceleration Solve a rw2 0 095m 7000 0 2 rad 60s 2 50999 04 m s2 9 81 m s2 5200 g m s2 Answer 5200 g m s2 3 Suppose a yo yo has a center shaft 0 300 cm in radius and that string is being pulled from it 10 points a If the string is stationary and the yo yo accelerates away from it at a rate of 1 70 m s2 what is its angular acceleration 5 points Given r 0 003m a 1 70 m s2 Find angular acceleration Solve angular acceleration a r 1 70 m s2 0 003 m 566 7 rad s2 Answer 566 7 rad s2 b What is the angular velocity after 0 750 s if it starts from rest 5 points Given angular acceleration 566 7 rad s2 Time 0 750s Find angular velocity Solve w at 566 7 rad s2 0 750s 425 rad s Answer 425 rad s c The outside radius of the yo yo is 3 50 cm In the reference fram of the yo yo s mass center what is the tangential acceleration of a point on its edge Given a 566 7 rad s2 r 0 035 m Find tangential acceleration Solve ta ar 566 7 0 035 19 83 m s2 Answer 19 83 m s2 4 Suppose a 57 0 kg gymnast climbs a rope a 8 points What is the tension in the rope if he climbs at a constant speed Given m 57 0 kg a g 9 80 m s2 Find tension Solve T ma 57 0 9 80 558 6 559 N Answer 559 N b 7 points What is the tension in the rope if he accelerates upward at a rate of 1 80 m s2 Given m 57 0 kg a 9 80 1 80 11 6 m s2 Find tension Solve T ma 57 0 11 6 661 2 661 N Answer 661 N 5 15 points The triceps muscle in the back of the upper arm extends the forearm This muscle in a professional boxer exerts a force of 2 00 10 3 N with an effective perpendicular lever arm of 4 00 cm producing an angular acceleration of the forearm of 130 rad s2 What is the moment of inertia of the boxer s forearm Given r 0 04 m F 2 00 x10 3 N l 130 rad s2 Find Moment of inertia Solve angular acceleration rF l 04 2 00 x 103 130 0 6 kg m2 Answer 0 6 kg m2 6 8 points a How much gravitational potential energy relative to the ground on which it is built is stored in an Egyptian pyramid given its mass is about 6 10 9 kg and its center of mass is 28 0 m above the surrounding ground 7 points Given m 6 x109 h 28 0 m g 9 80 m s2 Find energy Solve Energy mgh 6 …