Answer:
[tex]V(bar)=46.33(km/hr).[/tex]
Explanation:
Let's refer to the formula of average velocity.
Formula: [tex]V(bar)=\frac{td}{ct}[/tex], where td is the todal displacement, and ct is the change in time.
Since we're trying to find out the average velocity of the whole event (from time 0 when the car started moving to time 30 minutes when it finished the trip), we must take 30 minutes as our change in time.
Now, we need to find the distance traveled by the car on each instance of speed:
1. Distance covered with speed 1.
To find the covered distance, use the following formula.
[tex]d=vt[/tex], where "v" is velocity, and "t" is time.
Note. When using this type of formulas, all variables must match units. For example, say that your velocty is on km/hr, this means that the time or distance you input or calculate is going to be on kilometers or hours.
Find the value.
[tex]d=(61(km/h))(10(min))\\ \\d=610 (km).[/tex]
2. Distance covered with speed 2.
[tex]d=(39(km/h))(20(min))\\ \\d=780 (km).[/tex]
3. Find average velocity through the given formula.
Note. We add up both calculated distances to find the total displacement of the car.
[tex]V(bar)=\frac{td}{ct}\\ \\V(bar)=\frac{610(km)+780(km)}{30(min)}\\ \\V(bar)=46.33(km/hr).[/tex]
