Kinematics

[Hannibal Smith]

Hi guys and gals,

I am studying Physics at home and am stuck on some simple Kinematics questions. Y'know the sort, time, distance acceleration type puzzlers?

I am doing fine but in the book I am reading it does not give the formula for working out this little ditty out and I know it is something simple but I've juggled the equation around so much now I am getting sick.
The answer is 114.8km/h. How in the name of Decker do you get that answer? Here's the question:

A car is travelling along a road at 50km/h. If it accelerates uniformly at 1.5m/s2 - What speed will it reach in 12s?

Gotta be simple but...sigh..you try.

Please be a diamond someone and show all your working in a simple jargon-free dialogue!
And if anyone can give advice on the equations you need to get imbedded in your head for these questions I'd really dig it!

Thanks,

The Hannibal.

------------------
Let's go dirtbags!

[Bally Heck]

Alimentary my dear Hannibal.

50 km/h = 50000m / 3600s = 13.9m/s

1.5 m/s/s for 12 s = 18m/s

add 18m/s to 13.9 m/s comes to 31.9 m/s

which is

31.9 x 3600/1000 = 114.8 km/h

Brain the size of a planet me.

[This message has been edited by Bally Heck (edited 14 June 2001).]

[Hannibal Smith]

Nice one Bally, nice one. You smoke Cubans?

Hannibal.

[OnTheStep]

^^^which is basically one of the uniform motion equations put into words
where:
v1=50kph converts to:
50 x 1000/3600 = 13.888m/s so the units are concurrent with the acceleration

substitute into the equation:
(v2)=(v1)+(a)(t)
v2= (13.888 m/s)+ (1.5 m/s^2)(12s)
v2= 31.888 m/s
converted back:
31.888 x 3600/1000 = 114.8 kph

so for uniform motion, use:

v2=v1+(a)(t)
v2^2 = v1^2 + 2(a)(d)
d2=d1 + (v1)t +(a/2)(t^2)

a=accel
t=time
d=dist

have fun, enjoy the easy stuff while it lasts!

[This message has been edited by OnTheStep (edited 14 June 2001).]

[Bally Heck]

Hannibal
Rolled on the inside of a dusky maiden's thigh?

Si senor

[Hannibal Smith]

BA Baracas deals with the whys and where fors of ma Cubans.........(on communication with the dude) ....he say's yay! They're rolled on those thighs my man!

Hannibal.

[Hannibal Smith]

And the next part:

How long will it take to reach 150km/h?

Thanks for the time guys.

[2Bornot2B]

hey, onthestep, why are you a ramp rat with the type of knowledge you obviously possess?

i smoke cubans!

.............................................

once i thought i made a mistake, but i was wrong.

[Bally Heck]

C'mon Hannibal. Your worse than my Kids.
This one will cost you the dusky maiden.

150kph-114.8kph = 35.2kph = 9.8m/s / 1.5m/s/s = 6 and a bit seconds.

Have her gift wrapped and braced.

BH

[Hannibal Smith]

So why does it say the answer is 18.5s in the back of the book?

The maiden's getting her sexy strap-up sandals on but she no come till we getta de answer ma friend. I thought the answer would be 6 and a bit but hey.....the answer in the book differ.

Wind the chopper up Murdoch - we gotta be outa here soon.

The Hannibal.

[This message has been edited by Hannibal Smith (edited 17 June 2001).]

[OnTheStep]

<font face="Verdana, Arial, Helvetica" size="2">hey, onthestep, why are you a ramp rat with the type of knowledge you obviously possess?</font>

gotta do something when wx is bad. actually i'm enrolled in an aviation programe at a college and taking a number of engineering courses for it while i obtain my comm/multi-ifr (bloody slow way of doing it though, over three years)

[OnTheStep]

oh, by the way

v1=50 kph -&gt; 13.888 m/s
v2=150kph -&gt; 41.666m/s
a = 1.5 m/s^2

v2=v1+at
41.666m/s = 13.888m/s + 1.5 m/s^2(t)
27.779 = 1.5t
t=18.519s

cheers

[Bally Heck]

Sorry Hannibal.

Thought the question was how long it takes to reach 150kph from 114.8hph at which it was travelling when I last saw it.

Shoulda listened to my old rocket science teacher when he said "Bally my boy, never ever try rocket science after a night Pafos"