Need help with mathematics

[OptiSTR]

hey guys, so I watched this video:

on 8:00 he shows an equation where I cant menage to get the sane result as he does.

5.7T*9.8m/s2 = 55.9

while when I calculate it I get 547.428

am I missing something?

[SlyReaper]

Basic multiplication, it would seem. 5.7 times 9.8 is 55.86, which rounds to 55.9. You should have a calculator on your computer.

[Geredis]

5.7T*9.8m/s2 = 55.9

Looking at that...I'll guess that you're multiplying 5.7 by 96.2361 (the result of 9.81^2)...which, if I've done my maths right does come to 548.54577... Now, using your 9.8...I do get your answer (547.428) provided you did indeed square gravity (the 9.8).

Your problem is that the unit in question is m/s2... The ^2 is part of the units, denoting acceleration, basically. For the purposes of your calculations, you should have disregarded that... Thus, 5.7*9.8 comes to 55.86 (rounded to 55.9) or (if you use the traditional 9.81 for gravity...) 55.917. Both still round to 55.9.

EDIT:

Basic multiplication, it would seem. 5.7 times 9.8 is 55.86, which rounds to 55.9. You should have a calculator on your computer.

Now, Sly...as simple a mistake as it has been, I'd say that it's also quite understandable. Hell, if I didn't realise we were working with acceleration from gravity, I'd have probably made that same mistake if I was in enough of a rush.

Edited April 20, 2013 by Geredis
Adding reply to SlyReaper

[Tembaco]

A little more graphical notation:

What you are trying to calculate here is the weight(not the mass) of the vehicle. Weight is the force you put on the surface below you expressed in Newton.

F is in Newton

M is mass in kilograms

A is acceleration in meters per second per second

Of course if you use Tons for mass you get KiloNewtons or a thousand Newton.