520 points OSColPhys1 2.3.011 MyNotes Ask Your A student drove to the university

Question

520 points OSColPhys1 2.3.011 MyNotes Ask Your A student drove to the university from her home and noted that the odometer on her car increased by 13.0 km. The trip took 20.0 min. (a) What was her average speed? km/h (b) If the straight-line distance from her home to the university is 10.3 km in a direction 25.0° south of east, what was her average velocity? km/h (25° S of E) (c) If she returned home by the same path 7 h 30 min after she left, what were her average speed and velocity for the entire trip? average speed km/h average velocity km/h 1. My Notes Ask Your -20 points oscephys1 2.5034,XP An express subway train passes through an underground station. It enters at t 0 with an initial velocity of 23.0 m/s and decelerates at a rate of 0.150 m/s2 as it goes through. The station in 225 m long (a) How long is the nose of the train in the station? (b) How fast is it going when the nose leaves the station? (c) If the train is 130 m long, at what time t does the end of the train m/s leave the station? (d) What is the velocity of the end of the train as it leaves? m/s

Explanation / Answer

15)Given,

d = 13 km ; t = 20 min = 0.33 hr

a)v = d/t

v = 13/0.33 = 39.4 km/h

Hence, v = 39.4 km/h

b)v = 10.3/0.33 = 31.21 km/h

Hence, v = 31.21 km/h 25 deg S of E

c)distanc travelled in returning

d = 13 x 2 = 26 km

speed = 26/7.5 = 3.5 km/h

veocity = 0 since displacement is 0

average speed = 3.5 km/h ;

average velocity = 0 km/h

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