A car travels a distance A to B at a speed of 40 km/h and returns to A at a speed of 30 km/h. (1) What is the average speed for the whole journey? (ii) What is the average velocity?
Answers
Here's your answer!!
___________________________
Speed from A to B = 40km/h
Let the distance be x
So,
Time taken =
\begin{gathered} = > \frac{distance}{speed} \\ = > \frac{x}{40}h \end{gathered}
=>
speed
distance
=>
40
x
h
Now,
speed from B to A =30km/h
Let distance be x
So,
Time taken =
= > \frac{x}{30}h=>
30
x
h
We know that,
\begin{gathered}average \: speed = \frac{total \: distance \: travel}{total \: time \: taken} \\ = > \frac{x + x}{ \frac{x}{40} + \frac{ x }{30} } \end{gathered}
averagespeed=
totaltimetaken
totaldistancetravel
=>
40
x
+
30
x
x+x
\begin{gathered} = > \frac{2x}{ \frac{7x}{120} } \\ = > \frac{2x \times 120}{7x} \\ = > \frac{240x}{7} \end{gathered}
=>
120
7x
2x
=>
7x
2x×120
=>
7
240x
= > 34.28(approx)=>34.28(approx)
Hence,
Average speed from A to B then again B to A is 34.28 km/h
Now,
We have to find out the Average velocity
We know that,Velocity is the distance travelled per unit time in some specific direction but here the distance is being change .He moved from A to B in straight line but he changed his direction while moving from B to A.
Hence,
Average velocity will be 0.