#1

How in the world do I do this?

I know it's easy, I just didnt listen, and as a result have no clue what to do:

Some dudes cycle. They travel 6 km North, 4 km East, 6 km South, 4 km East, 3 km north.

If the ride took them 10 minutes, what is their average velocity?

Thanks...sorry about me being a retarded monkey.

I know it's easy, I just didnt listen, and as a result have no clue what to do:

Some dudes cycle. They travel 6 km North, 4 km East, 6 km South, 4 km East, 3 km north.

If the ride took them 10 minutes, what is their average velocity?

Thanks...sorry about me being a retarded monkey.

#2

13.8 km/hr

#3

13.8 km/hr

Isn't that just their average speed? Or am I confused?

#4

Work out where he moved to relative from his start point.

Work out the distance between start point and end point (a direct distance, not going round all the roads etc.)

Divide by time taken.

Distance should be in metres and time in seconds.

Work out the distance between start point and end point (a direct distance, not going round all the roads etc.)

Divide by time taken.

Distance should be in metres and time in seconds.

#5

velocity = mass x acceleration

#6

ok, 13.8 km/hr north

velocity is just speed with a direction

velocity is just speed with a direction

#7

velocity = displacement / time.

He travels a total of 9km north, 6km South and 8km East.

That's the same as travelling 3km North and 8km East.

Using Pythagoras' theorem:

Displacement = √(9 + 64) = √73

Velocity = √73 / 600 * 1000 (600 seconds in 10 minutes, 1000 metres in a kilometre)

He travels a total of 9km north, 6km South and 8km East.

That's the same as travelling 3km North and 8km East.

Using Pythagoras' theorem:

Displacement = √(9 + 64) = √73

Velocity = √73 / 600 * 1000 (600 seconds in 10 minutes, 1000 metres in a kilometre)

#8

Work out where he moved to relative from his start point.

Work out the distance between start point and end point (a direct distance, not going round all the roads etc.)

Divide by time taken.

Distance should be in metres and time in seconds.

You mean his displacement? It's 8.5 km.

8500m/600s

is 14.1 m/s?

#9

I think I get the same as Frenchy

#10

im not 100% sure, but since its 'velocity' i think you would need to resolve into components and find the angle of the resultant (or maybe im being silly and its much simpler)

#11

Crap, you guys just confused me way more.

#12

Okay, you understand the difference between velocity and speed, right?

Your understand Pythagoras' theorem, right?

That pretty much sums it up.

He goes north 6 kilometres and then south 6 kilometres (ignore the 4km east in the middle).

These cancel out. After that, he goes back north 3km. So he's now 3km north of his starting point.

He travelled west 0km and east 8km, so he's not just 3km north, he's also 8km east from his start point. Helping?

You now need to know how far his finishing point is from his start point. To do this, we use Pythagoras' theorem of right angled triangles. This works out his displacement.

10 mins = 600 seconds

1000m in 1km, so you multiply route73 by 1000 to get it in metres. Then divide by 600. This puts in in metres per second, the SI unit for velocity.

Your understand Pythagoras' theorem, right?

That pretty much sums it up.

He goes north 6 kilometres and then south 6 kilometres (ignore the 4km east in the middle).

These cancel out. After that, he goes back north 3km. So he's now 3km north of his starting point.

He travelled west 0km and east 8km, so he's not just 3km north, he's also 8km east from his start point. Helping?

You now need to know how far his finishing point is from his start point. To do this, we use Pythagoras' theorem of right angled triangles. This works out his displacement.

10 mins = 600 seconds

1000m in 1km, so you multiply route73 by 1000 to get it in metres. Then divide by 600. This puts in in metres per second, the SI unit for velocity.

*Last edited by JamieB at Jan 22, 2007,*

#13

How in the world do I do this?

I know it's easy, I just didnt listen, and as a result have no clue what to do:

Some dudes cycle. They travel 6 km North, 4 km East, 6 km South, 4 km East, 3 km north.

If the ride took them 10 minutes, what is their average velocity?

Thanks...sorry about me being a retarded monkey.

Displacement does not matter here at all.

v = s / t

t=600 secs

s = 6 + 4 + 6 + 4 + 3 = 23 km = 2300 m

v = 2300 m / 600 s = 23/6 m/s

There...almost 4 m/s

edit : lol forgot it's velocity ... that makes vectors come in to the equation disregard my post

#14

^Wrong.

Velocity and speed are two different things.

Velocity = DISPLACEMENT / time

Speed = DISTANCE / time

Velocity and speed are two different things.

Velocity = DISPLACEMENT / time

Speed = DISTANCE / time

#15

if it helps:

speed= scalar quantity so only magnitude (i.e. 10m/s) but no direction

velocity= vector quantity so both magnitude and direction (i.e. 10m/s at 090° bearing)

speed= scalar quantity so only magnitude (i.e. 10m/s) but no direction

velocity= vector quantity so both magnitude and direction (i.e. 10m/s at 090° bearing)

#16

Bronek for the loss

#17

do you know how to resolve forces into components? which subject is this like physics or math mechanics?

#18

This isn't about putting forces into components. It's just a simple displacement/time equation.

#19

Bronek for the loss

Nuh-uh ... i realized it so I edited

^Wrong.

Velocity and speed are two different things.

Velocity = DISPLACEMENT / time

Speed = DISTANCE / time

read primary reply

#20

Jamie you nerd, it's not 'ms^-1' it's m/s. Stop showing off

#21

Jamie you nerd, it's not 'ms^-1' it's m/s. Stop showing off

sorry tubby

I mean, chubby

#22

You know what? I'm not going to do it. There, I said it. So there.

#23

Dude, we just showed you step by step how to do it

Have you tried Google? Maybe it can explain better.

Have you tried Google? Maybe it can explain better.

#24

well if it was components then frenchyfungus is right and the bearing of the resultant force would be 90° - (tan^-1(3/8))

#25

Frenchy just did a displacement/time equation, like was needed

This isn't about forces

#26

It's ok guys, I gave up.

#27

he didnt actually (or atleast that's what i think)....or maybe im just overcomplicating things heck when they say velocity they probably just mean speed; at earlier levels the two terms are frequently swapped around....my bad i guess

#28

NO!

No you didn't.

Right;

You know the difference between velocity and speed, right?

EDIT: No, it's referring to velocity, it's just a matter of working out the displacement and dividing it by the time. Nothing more

No you didn't.

Right;

You know the difference between velocity and speed, right?

EDIT: No, it's referring to velocity, it's just a matter of working out the displacement and dividing it by the time. Nothing more

#29

velocity is a vector so 'technically' it would need a direction....

#30

NO!

No you didn't.

Right;

You know the difference between velocity and speed, right?

EDIT: No, it's referring to velocity, it's just a matter of working out the displacement and dividing it by the time. Nothing more

How about you just give me the answer and I say thanks?

#31

The answer is (route73*1000)/600

As in the square root of 73 (somewhere between 8 and 9) multiplied by 1000 then divided by 600.

I don't think he's studying for a degree, classical gas, it doesn't need to get that technical.

Okay, route 73 is somewhere between 8.5 and 8.55 (can't find a square root button on MS calculator), so you can put that to 8.5 to 2 significant figures.

Times by 1000 = 8500

8500/600

= 14.2ms^-1 (3sf)

As in the square root of 73 (somewhere between 8 and 9) multiplied by 1000 then divided by 600.

I don't think he's studying for a degree, classical gas, it doesn't need to get that technical.

Okay, route 73 is somewhere between 8.5 and 8.55 (can't find a square root button on MS calculator), so you can put that to 8.5 to 2 significant figures.

Times by 1000 = 8500

8500/600

= 14.2ms^-1 (3sf)

*Last edited by JamieB at Jan 22, 2007,*

#32

v = d/t?

#33

How about you just give me the answer and I say thanks?

14.24 m/s

#34

14.24 m/s

Thanks.

#35

sorry tubby

I mean, chubby

And I suppose you do m/s/s as ms^-2?

#36

yea i guess so JamieB, sorry i just had an A level mechanics exam, so you know, my head is still into 'math mode'

#37

Thanks.

You won't learn that way!

#38

yeah, I know what you mean. You just gotta know when to go back to basics

And yes, I do put ms^-2. When you get to A-level, you have to. Just as you have to put distance/m when labelling axes, not distance (m).

And yes, I do put ms^-2. When you get to A-level, you have to. Just as you have to put distance/m when labelling axes, not distance (m).

#39

It's velocity, so you

*need*to say the direction as well. You'll lose marks for it if you don't.
#40

It's velocity, so youneedto say the direction as well. You'll lose marks for it if you don't.

well atleast someone agrees