Answer:
a) ![t_1=338.4615\ s](https://tex.z-dn.net/?f=t_1%3D338.4615%5C%20s)
b) ![t=1386.0805\ s](https://tex.z-dn.net/?f=t%3D1386.0805%5C%20s)
c) ![t=23.1013\ min](https://tex.z-dn.net/?f=t%3D23.1013%5C%20min)
d) ![d=4400\ m](https://tex.z-dn.net/?f=d%3D4400%5C%20m)
e) Since Dave starts from house and finally returns to the house so displacement is zero.
Explanation:
Given:
- distance between the house and the store,
![s=2.2\ km=2200\ m](https://tex.z-dn.net/?f=s%3D2.2%5C%20km%3D2200%5C%20m)
- speed of driving from house to store,
![v_1=-6.5\ m.s^{-1}](https://tex.z-dn.net/?f=v_1%3D-6.5%5C%20m.s%5E%7B-1%7D)
- speed of driving back from store to house,
![v_2=2.1\ m.s^{-1}](https://tex.z-dn.net/?f=v_2%3D2.1%5C%20m.s%5E%7B-1%7D)
Since the store is located towards east from his house and the velocity in this direction is taken negative and contrary to this the velocity in the west direction is taken positive.
a)
time taken in reaching the store:
![t_1=\frac{s}{v_1}](https://tex.z-dn.net/?f=t_1%3D%5Cfrac%7Bs%7D%7Bv_1%7D)
![t_1=\frac{-2200}{-6.5}](https://tex.z-dn.net/?f=t_1%3D%5Cfrac%7B-2200%7D%7B-6.5%7D)
![t_1=338.4615\ s](https://tex.z-dn.net/?f=t_1%3D338.4615%5C%20s)
b)
Now the time taken in returning form the store:
![t_2=\frac{s}{v_2}](https://tex.z-dn.net/?f=t_2%3D%5Cfrac%7Bs%7D%7Bv_2%7D)
![t_2=\frac{2200}{2.1}](https://tex.z-dn.net/?f=t_2%3D%5Cfrac%7B2200%7D%7B2.1%7D)
![t_2=1047.6190\ s](https://tex.z-dn.net/?f=t_2%3D1047.6190%5C%20s)
therefore total time taken by the trip:
![t=t_1+t_2](https://tex.z-dn.net/?f=t%3Dt_1%2Bt_2)
![t=338.4615+1047.6190](https://tex.z-dn.net/?f=t%3D338.4615%2B1047.6190)
![t=1386.0805\ s](https://tex.z-dn.net/?f=t%3D1386.0805%5C%20s)
c)
the time taken by the trip in minutes:
![t=\frac{1386.0805}{60}](https://tex.z-dn.net/?f=t%3D%5Cfrac%7B1386.0805%7D%7B60%7D)
![t=23.1013\ min](https://tex.z-dn.net/?f=t%3D23.1013%5C%20min)
d)
distance travelled in the whole trip:
![d=2\times s](https://tex.z-dn.net/?f=d%3D2%5Ctimes%20s)
![d=2\times 2200](https://tex.z-dn.net/?f=d%3D2%5Ctimes%202200)
![d=4400\ m](https://tex.z-dn.net/?f=d%3D4400%5C%20m)
e)
Since Dave starts from house and finally returns to the house so displacement is zero.