Homework 1 Begin Date: 1/15/2018 12:00:00 AM -- Due Date: 1/29/2018 11:59:00 PM
ID: 1574052 • Letter: H
Question
Homework 1 Begin Date: 1/15/2018 12:00:00 AM -- Due Date: 1/29/2018 11:59:00 PM End Date: 1/29/2018 11:59:00 PM (6%) Problem 18: A car speeds past a stationary police officer while traveling 105 km/h. The officer immediately begins pursuit at a constant acceleration of 9.7 km/h/s, just as the driver passes the officer Randomized Variables = 105 km/h a = 9.7 km/h/s × 50% Part (a) How much time, in seconds, will it take for the police officer to catch up to the speeding car, assuming that the car maintains a constant speed? Grade Surnmary Deductions Potential 10.8251 2% 98% 7 89 HOME Submissions Attempts remaining: 6 (0% per attempt) detailed view cotanO asinO acos0 atanO acotansinhO coshO tanhOcotanhO Degrees Radians 0% 0 END VO BACKSPACE E CLEAR Submit Hint Feedback I give up! Hints: 1 for a 2% deduction. Hints remaining: 1 Feedback: 2% deduction per feedback. How far will the speeding car have traveled when the police car catches up? Careful about the units here 50% Part (b) How fast, in kilometers per hour, will the police officer be traveling at the time he catches up to the driver?Explanation / Answer
a)
Vc = speed of car = 105 km/h = 29.2 m/s
a = 9.7 km/h/sec = 2.7 m/s2
let the police catch the car after "t" seconds
displacement of police = displacement of car
Yp = Yc
Vop t + (0.5) a t2 = Vc t
(0) t + (0.5) (2.7) t2 = 29.2 t
t = 21.6 sec
b)
Vf = final velocity of police
using the equation
Vf = Vop + at
Vf = 0 + 2.7 x 21.6
Vf = 58.32 m/s = 2010 km/h
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