Exam 1 7 questions in 4 pages for 50 minutes in February 5 2013 Course PHYS1111 1 25pm Instructor Tho Nguyen First and last name Student ID 1 Choose whether each of the following statements is true T or false F An object that is accelerating must have a nonzero average velocity An object with a nonzero acceleration at some instant of time can have a velocity of zero at that instant Instantaneous velocity has the same magnitude as instantaneous speed Both displacement and distance can be negative An object with a nonzero velocity can have an acceleration of zero Velocity and speed are the same 2 The graph shows the acceleration of a car in one dimension which is initially driving in the forward direction a At what time does it have maximum forward positive velocity b At what time does it have maximum acceleration 3 The velocity vector V1 has a magnitude of 3 0 m s and is directed along the x axis The velocity vector V2 has a magnitude of 4 0 m s and can be in any direction The sum of the two is V3 so that V3 V1 V2 The x component of V3 can be 1 0 m s The magnitude of V3 can be 6 0 m s The magnitude of V3 can be 8 0 m s The y component of V3 can be 5m s The magnitude of V3 can be 0 0 The magnitude of V3 can be 7 0 m s 4 The plot shows the trajectory height versus distance of an object launched at an angle of with the horizontal and an initial speed v0 Circle the best answer i At what position in the graph is the magnitude of velocity the largest a d 0 00m b d 0 60m c d 1 22m ii What is the magnitude of the acceleration of the object at the highest point of the trajectory a g b g sin c g cos iii What is the magnitude of the velocity of the object at the highest point of the trajectory a v0 sin b v0 cos c v0 5 A park ranger driving on a back country road suddenly sees a deer frozen in the headlights The ranger who is driving at 11 0m s immediately applies the brakes and slows with an acceleration of 3 80m s2 a If the dear is 20 0m from the ranger s vehicle when the brakes are applied how close does the car come to hitting the deer b How much time does it take for the ranger s vehicle to stop 6 A projectile is launched from ground level at 33 0 m s at an angle of 30 0 above horizontal Use the launch point as the origin of your coordinate system a Calculate the initial velocity in x and y direction b How far downrange the horizontal distance from the origin was the projectile when it reached the highest point in its flight c Calculate the velocity of the object when it travel distance d 70m in x direction 7 You are in a hot air balloon rising from the ground at a constant velocity of 2 80 m s upward To celebrate the takeoff you open a bottle of champagne expelling the cork with a horizontal velocity of 6 00 m s relative to the balloon a What is the initial speed of the cork as seen by your friend on the ground b What is the initial direction of the cork as seen by your friend Give your answer as an angle relative to the horizontal
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