Question

1. a car first travels 22.0 me and then turns and travels 13.8 m s.

a. draw a vector diagram and find the total displacement of the car.
b. if the car completed the trip in 4.5 minutes, calculate the cars average speed.

1. a car moves with a steady speed of 7.4 km/h for 35.0 min, then 16 km/h for 18.0 minutes.

a) what was the total distance travelled during the whole trip?
b) what is the average speed for the whole trip?

Explanation:

Step1: Calculate distance for first - part of 6

Convert time to hours. 35.0 min = $\frac{35}{60}$ h.
$d_1 = v_1t_1=74\times\frac{35}{60}\text{ km}$
$d_1=\frac{74\times35}{60}\text{ km}\approx43.17\text{ km}$

Step2: Calculate distance for second - part of 6

Convert 18.0 min to hours. 18.0 min = $\frac{18}{60}$ h.
$d_2 = v_2t_2 = 86\times\frac{18}{60}\text{ km}$
$d_2=\frac{86\times18}{60}\text{ km}=25.8\text{ km}$

Step3: Calculate total distance for 6(a)

$d = d_1 + d_2$
$d=43.17 + 25.8=68.97\text{ km}$

Step4: Calculate total time for 6(b)

$t=t_1 + t_2=\frac{35 + 18}{60}\text{ h}=\frac{53}{60}\text{ h}$

Step5: Calculate average speed for 6(b)

$v_{avg}=\frac{d}{t}=\frac{68.97}{\frac{53}{60}}\text{ km/h}$
$v_{avg}=\frac{68.97\times60}{53}\text{ km/h}\approx78.0\text{ km/h}$

Answer:

a) 68.97 km
b) 78.0 km/h