Explanation
Average speed is defined as the total distance travelled by the time taken
[tex]\begin{gathered} Speed_{average}=\frac{total\text{ distance}}{\text{total time}} \\ \end{gathered}[/tex]Step 1
find the total distance
[tex]\text{distance =sp}eed\cdot time[/tex]hence:
a)distance 1
1.00 h at 10.0 km/h
[tex]\begin{gathered} \text{distance 1=10 }\frac{\operatorname{km}\text{ }}{h}\cdot1\text{ hour} \\ \text{distance 1}=10\text{ km} \end{gathered}[/tex]b) distance 2
2.00 h at 20.0 km/h.
[tex]\begin{gathered} \text{distance =sp}eed\cdot time \\ \text{distance }2=20\frac{\operatorname{km}}{h}\cdot2\text{ hours} \\ \text{distance }2=40\text{ km} \end{gathered}[/tex]so, the total distance is
[tex]\begin{gathered} \text{total distance = 10 km+40 km} \\ \text{total distance =}50\text{ km} \end{gathered}[/tex]Step 2
Now, let
total distance = 50 km
total time= 1 hour+2 hours= 3 hours
replace in the formula
[tex]\begin{gathered} Speed_{average}=\frac{total\text{ distance}}{\text{total time}} \\ Speed_{average}=\frac{50\text{ km}}{3\text{ hours}} \\ Speed_{average}=16.67\text{ km per hour} \end{gathered}[/tex]Step 3
finally, let the answer is SI units:
the units of speed is meter per second or km per hour, so let's convert it
[tex]\begin{gathered} \\ Speed=16.67\frac{\operatorname{km}}{h}(\frac{1\text{ hour}}{3600\text{ sec}})(\frac{1000\text{meters}}{1\text{ km}}) \\ Speed=4.63\text{ meters per second} \\ Speed=4.63\text{ }\frac{m}{s} \end{gathered}[/tex]I hope this helps you
