The City University of New York City College of Technology Physics 1441 Exam 1 F

Question

The City University of New York City College of Technology Physics 1441 Exam 1 Fall 2017 Exam consists of six problems. To get full or particle credit show all the work in the booklet provided. Frame your answer. Good luck! 1. A motorist drives along a straight road at a constant speed of 15 m/s. She passes a motorcycle police officer moving at constant of 8 m/s. After 2.0 sec the officer starts accelerating at 2.0 m/s2 to overtake the motorist. Determine a) time it will take the police officer to reach the motorist. b) speed and total displacement of the police officer as he overtakes the motorist 2. A particle moves in the xy plane, starting from the origin at t-0 with initial velocity having an x component of 20 m/s and a y component of-15 m/s. The particle experiences an acceleration in the x direction, given by ax=4.0 m/s2

Explanation / Answer

let the motorist passes police motorcycle at t = 0

then at time t, distance covered by motorist = 15t

distance covered by police officer = 8 x 2 + 8(t-2) + 0.5 x 2 x (t-2)2

now to overtake, both distance will be equal

15t = 8t + (t-2)2

7t = t2 - 4t + 4

=> t2 - 11t + 4 = 0

=> t = 10.6235 s

the speed of police officer = 8 + 2(t-2) = 2t + 4 = 25.247 m/s

displacement = 15t = 159.35 m

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