Conversion

[Kdawg]

How do you convert m/s^2 to km/h?

[plover]

At least in the form you asked the question, you can't. m/s2 is a unit for acceleration while km/h is a unit for speed.

[KaneOris]

well you can if you have the delat t of a

[KaneOris]

But if you are trying to convert ms^-1 than its rather easy, theres a couple ways of doing it.
I do it like such
((36km/60)/60)*1000
which is equal to 10ms^-1

Theres some really easy way to do it, but this one never fails and it doesnt take that much longer so i just use this one.

[Kdawg]

Oh, that would make sence wouldnt it, lol. Im trying to figure out this problem.
A bus traveling at +29 km/h accelerates at a constant +3.7 m/s2 for 6.3 s. What is its final velocity in km/h?
This is my work so far, what am I doing wrong.
Vi = 29Km/h
a = 3.7m/s^2
t = 6.3s
Vf = ?

Vf = Vi + at
Vf = 29 + 3.7 * 6.3
Vf = 52 - With right sig figs

[plover]

Looks good to me.

[Kdawg]

Thats what I thought but the damn webassign keeps marking it wrong.

[KaneOris]

I can see why from here,
Vf = Vi +at
SI UNITS!
Velocity SI unit is ms^-1
Therefore 29kmh^-1
Needs to be converted to ms^-1

[KaneOris]

What is its final velocity in km/h?
And then convert it back

[KaneOris]

You have to remember to convert stuff, i will never forget, i lost 15 marks out of 50 on my last exam from not converting to the SI units

[Kdawg]

I converted 29km/h to 8.0556m/s the multiplied 8.0556 + 3.7 * 6.3 = 30.6256
then converted that to 110. That obviously isnt right, what am I doing wrong.

[plover]

Bleah. Of course. I wasn't looking at the units.

[KaneOris]

Seems right to me... Remember, think of how long 6.3 seconds is when your accelerating in a car. Like when you go onto a freeway, you would really only accelerate for about 3 seconds to get to 100km, from about 50..., so 6 seconds is actually a long time to accelerate for

[tyco05]

I converted 29km/h to 8.0556m/s the multiplied 8.0556 + 3.7 * 6.3 = 30.6256
then converted that to 110. That obviously isnt right, what am I doing wrong.


Try evaluating this again I don't seem to get the same answer for 8.05556+(3.7*6.3) as you do.

(and hence the converted figure is different as well)

[tyco05]

Seems right to me... Remember, think of how long 6.3 seconds is when your accelerating in a car. Like when you go onto a freeway, you would really only accelerate for about 3 seconds to get to 100km, from about 50..., so 6 seconds is actually a long time to accelerate for

This really depends on how hard you put your foot on the accelerator (or how good your car is!)

[KaneOris]

Yes, but you know what i mean, 6.3 seconds is a long time to accelerate, although the sound of it isnt very much, its a pain in the A$$ if you look at your watch and wait for 6 or 7 seconds to pass...