Kinematics
 

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!

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).]

Nice one Bally, nice one. You smoke Cubans?

Hannibal.

^^^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).]

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

Si senor

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.

And the next part:

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

Thanks for the time guys.

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.

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

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).]

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)

oh, by the way

v1=50 kph -> 13.888 m/s
v2=150kph -> 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

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"