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3 years ago

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A motorist drives north for 36.0 minutes at 96.0 km/h and then stops for 15.0 minutes. He then continues north, traveling 130 km

in 2.20 h. (a) What is his total displacement? km
(b) What is his average velocity? km/h

1 answer:

Over [174]3 years ago

8 0

Answer:

a) $d=187.6km$

b) $v=61.5km/h$

Explanation:

First we convert our minutes to hours so we work always in the same units.

$36min=36min(\frac{1h}{60min})=0.6h$

$15min=15min(\frac{1h}{60min})=0.25h$

Where we used the fact that 1 hour are 60 min, thus the multiplying factor is equal to 1 (not altering the time, just changing the units).

a) On the first part the motorist travels a distance $d_1=v_1t_1=(96km/h)(0.6h)=57.6km$ , and on the second part he travels $d_2=130km$ .

The total displacement is $d=d_1+d_2=57.6km+130km=187.6km$

b) The average velocity is the relation between the total displacement and the time taken to cover it. Our total time is t=0.6h+0.25h+2.2h=3.05h, thus we have:

$v=\frac{187.6km}{3.05h}=61.5km/h$

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