Really easy question but answers wrong? From: Dot Point Preliminary Physics 1.5.5 (c) (2 Viewers)

[dkazzle]

The question is:
"A car takes 2.5 hours to travel along the 150 km road from X and Y as shown in the diagram at a constant speed of 60kph. X and Y are 120km apart." The diagram is just X and Y apart with a curvy line connecting them to show the road.

The question 1.5.5(c) is: "Calculate the car's average speed." (edit)

The answer states it is 72kph. Is that right? Isn't average speed = total distance / total time ; which would mean it's 150/2.5 = 60kph.

Can someone please confirm/check this for me? Is there some sort of trick question I'm somehow missing? :\

thanks


*edit: I typed the wrong question lol, sorry about that. But thanks for the replies and help!

 

[RealiseNothing]

Re: Really easy question but answers wrong? From: Dot Point Preliminary Physics 1.5.5

 

[fortune_cookie]

Re: Really easy question but answers wrong? From: Dot Point Preliminary Physics 1.5.5

constant speed of 60kph

answer is 60

 

[fortune_cookie]

Re: Really easy question but answers wrong? From: Dot Point Preliminary Physics 1.5.5

It is if the velocity is constant, which is specified in the question. Also, the question mentions nothing about direction. Remember velocity is a vector. It has magnitude and a DIRECTION. Given the question says the road is curvy, it is possible that the directions are not the same.

 

[RealiseNothing]

Re: Really easy question but answers wrong? From: Dot Point Preliminary Physics 1.5.5

It is if the velocity is constant, which is specified in the question. Also, the question mentions nothing about direction. Remember velocity is a vector. It has magnitude and a DIRECTION. Given the question says the road is curvy, it is possible that the directions are not the same.

I just checked the book and the question actually asks for average speed, not instantaneously velocity.

So not sure why he said instantaneous velocity in the first place.

 

[someth1ng]

Re: Really easy question but answers wrong? From: Dot Point Preliminary Physics 1.5.5

Well, if it's asking for:
Average Velocity=120/2.5=48kph (direction of X to Y)
Average Speed=Given as 60kph constant

 

[dkazzle]

Re: Really easy question but answers wrong? From: Dot Point Preliminary Physics 1.5.5

Thanks for the replies and help! So it is 60kph (for average speed).. answers are wrong, yeh?
And sorry, I actually mistyped the question as I was copying onto here because I was in a bit of a rush lol