Slowly does it...

Number Theory Level 1

A sports car travels at 60 mph northwards along a motorway for one hour, and then travels at 60 mph southwards for an hour, to return to its starting place. Find the average speed of the car for the two hours.

80 mph 120 mph 60 mph 30 mph

2 solutions

X X
Aug 6, 2018

It is always traveling at 60mph,so of course the average speed is 60mph...

Yes... that is the point quite plainly if you don't over complicate the situation. If you see that straight away, then you are mathematically minded, and you oversee the words and just focus on numbers. Well done.

Surayyah Aziz - 2 years, 10 months ago

Surayyah Aziz
Aug 6, 2018

Solution: 60 mph

Explanation: The total distance travelled is 120 miles, but the displacement is zero. The length of the journey spans over 2 hours. The average speed for the two hours = $\frac{120}{2}$ = 60 mph

Pardon my ignorance but may I know what is displacement is zero

Mohammad Farhat - 2 years, 10 months ago

Hi Mohammad, Displacement is the shortest distance between two points. For example, if you had to get to a shop for you house, you could walk straight down the road to get to the shop, or all around lots of roads, and then eventually reach the shop. Here the shortest way is to walk straight down the road. And so the distance here would be displacement.

Dictionary: A displacement is a vector whose length is the shortest distance from the initial to the final position of a point P.

Surayyah Aziz - 2 years, 10 months ago

People like you help make the world better

Mohammad Farhat - 2 years, 10 months ago

@Mohammad Farhat – Thank you, Your comment has made my day. (-:

Surayyah Aziz - 2 years, 10 months ago

@Surayyah Aziz – Same to you

Mohammad Farhat - 2 years, 10 months ago

I thankfully now learnt it from the courses and it was you who sparked my interest.

Mohammad Farhat - 2 years, 9 months ago

Slowly does it...

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