Question

A boat travels 50 km east, then 120 km north and finally it comes back to the starting point through the shortest distance.
The total time of journey is 3 hours. What is the average velocity in km/hr, over the entire trip.?

The answer is 0
I want the steps and explanation ​

Answer 1

We know that,

The boat moves 50 km towards the East, then to North 120 km.

Now the shortest distance between those 2 points would be its displacement which is a straight line,

Now, if we graph this, we would get a triangle

Let the starting point be A, then it moves East 50km, let it end at B, then from B it moves North 120km to point C.

Now, AC will be a straight line moving South west, as it is the displacement.

Now, we know that, directions are perpendicular to it adjacent directions

For ex :-

North is perpendicular to East and West.

South is perpendicular to East and West.

Thus ,

∠B = 90° [East is perpendicular to North]

Hence, ABC is a right angled triangle

Thus,

By Pythagoras theorem

AB² + BC² = AC²

AC² = 50² + 120²

AC² = 2500 + 14400

AC² = 16900

AC = √16900

AC = 130km

Now,

Average Speed = Total Distance/Total Time

Total Distance = 50 + 120 + 130

= 250 km

Total Time = 3 hrs

Hence,

S(av.) = 300/3

S(av.) = 100 km/h

Thus,

The Boat travelled the total distance with an average speed of 100 km/h.

Answer 2

Step-by-step explanation:

It's even clearly that i comes to starting point

that is initial point

hence final position is same to that of initial position so displacement is zero

to find velocity we have the formula that is

v=d/t

since displacement is zero

velocity is zero