Got an exam in a month, try this one out as a sample (got a few other beautys as samples)

 

A car travels at a constant speed for 1/4 of a kilometer in 29.2 seconds. During this time the speedometer registers 22MPH.

Is this true speed and if not what is the percentage difference?

Answers to 2 significant figures.

 

Now, I am not all that bad at maths (well, am sh1te really) and cannot work this fuc

 

I have been given a clue that MPH to ms^-1 = x 0.447m WTF!!!!!!!

ms^-1 = x 0.447m

 

denotes 1mph = 0.447meters per second

 

250 / 29.2 = 8.56meters a second

 

8.56 / 0.447 = 19.15 mph

 

22 - 19.15 = 2.85mph out

 

2.85/22 * 100 = ~13% out (12.95%)

 

 

i think lol

Car is doing 250 meters in 29.2 secs

That's 8.8616438 meters per sec (250/29.2)

 

22mph is 9.834 meters per sec (22 X 0.447)

 

So the car is doing 8.861638 m/sec but speedo reads 9.834 m/sec

 

9.834 / 8.56164 = 1.1486

 

So the car speedo reads 114.86% of the true speed.

 

That's 100% plus 14.86%

 

So it's overreading by 15% (to two significant figures)

 

(I think - although I did used to enjoy maths - sad vvanker)

DIdn't see MIke's post - I'm probably wrong - will check

Ferk...u 2 are good....but both have different aswers

 

 

Who is right as both make sense....

 

 

When we get to the bottom of this I will post another....

In Mike's answer, 13% is 13% of the speedo reading.

In mine, 15% is a part of the actual true speed.

 

I'd go with his answer but I'm not sure.

The bit that kills me is the ms^-1..........

Anyone who can explain that is a god as my brain has been fried today (hence not at southend meet)

so we do the MPH thing and MS^-1 (0.447) rears its head...to the power of -1???? WHAT...

IAM GOING TO FAIL!!!!!!!

ms^-1

 

the -1 means constant speed,

 

10ms^-1

 

1second = 10ms

2second = 10ms

3second = 10ms

 

ms ^ -2

 

this is acceleration, it means you are accelerating at that speed every second

 

so

 

10ms^-2 means that

 

1 second = 10ms

2 second = 20ms

3 second = 30ms

If a cars travelling at 22MPH, then the driver should be pulled for kerb crawling!!!!

The little arrow signifies to the power (as in squared, cubed etc)

 

In this case you could say ms^-1 is m/s as they mean the same thing.

 

And you can swap the / for 'divided by' or 'per'

 

So ms^-1 means 'meters per second'

ms^-1 is metres per second (which denotes constant speed)

 

ms^-2 would be metres per second, per second (which would denote acc/decceleration)

If a cars travelling at 22MPH, then the driver should be pulled for kerb crawling!!!!

you are toooo right mate.......but.....

The little arrow signifies to the power (as in squared, cubed etc)got that bit

In this case you could say ms^-1 is m/s as they mean the same thing.

 

And you can swap the / for 'divided by' or 'per'

 

So ms^-1 means 'meters per second'

 

its the -1 (power of) thats killing me....cant see the logic (but algebra aint about that)....but you 2 are convincing me...

 

OK, will have a go based on your answers and then do another if you want.....haha...back to school...? (but harder????)

positive 'power of' means multiplied by that many times.

negative 'power of' mean divided by that many times, like this case where it's meters divided by seconds (just once!)

eg.

 

10^2 = 100

10^-2 = 0.01

eg.

 

10^2 = 100

10^-2 = 0.01

 

 

Wouldn't 10^-2 be 0.1? Surely you just shift the decimal point one place each time so it goes from 10 to 1, then to 0.1? Ten divide by ten, divide by ten?

Wouldn't 10^-2 be 0.1? Surely you just shift the decimal point one place each time so it goes from 10 to 1, then to 0.1? Ten divide by ten, divide by ten?

 

Nah...10^0=1 10 ^-1=0.1 10^2=0.02, etc,,,

 

Thanks for the help by the way,,,making sense now...at lllllllllast!!!!

I did a degree in Maths :o but Hellboy has been up since 2am this morning so my brain is mush lol

I did a degree in Maths :o but Hellboy has been up since 2am this morning so my brain is mush lol

 

Whats.......

 

13321-

13286

 

:rofl: :rofl: :rofl: :rofl:

:xxx: :rofl:

Whats.......

 

13321-

13286

 

:rofl: :rofl: :rofl: :rofl:

 

:slap: :rofl: :rofl:

Car is doing 250 meters in 29.2 secs

That's 8.8616438 meters per sec (250/29.2)

 

 

 

 

 

 

250/29.2 = 8.56

 

or is my calculator busted?

8.5616438356164383561643835616438 to be exact :tongue: ;)

8.5616438356164383561643835616438 to be exact :tongue: ;)

 

What sort of calculator are you using to get that many digits :confused: :D

What sort of calculator are you using to get that many digits :confused: :D

 

 

he is using his toes lol

Sorry Duff it's not exact.

 

The figures will cycle, ie repeating "43835616" for as long as you care to type them!! :tongue: :slap:

 

 

Simon.

Sorry Duff it's not exact.

 

The figures will cycle, ie repeating "43835616" for as long as you care to type them!! :tongue: :slap:

 

 

Simon.

 

 

I dunno..... :rolleyes: you'll be wanting ****in blood next ffs :tongue: :rofl: