Gravity 10 or 9.8? and weight calculations for dummies

EnlightenedOne
Posts: 37
Joined: Wed Sep 08, 2010 2:57 pm

Gravity 10 or 9.8? and weight calculations for dummies

Post by EnlightenedOne »

Hey there I am wondering why gravity is set to 10 by default in all the bullet projects when earths gravity is 9.8? I am trying to figure out how to quanitfy mass into weight.

weight = gravity * mass
http://wiki.answers.com/Q/If_a_person_w ... n_the_moon
-6000 = -10 (on y axis) * 600 (random units of mass in bullet simulation).

As far as I am aware 1kg = 9.81 newtons (on earth). So my gravity is slightly greater than the weight of a kg?
http://wiki.answers.com/Q/How_many_kg_is_1_Newton

So if I have 10 newtons per 1Kg trying to make kg a measurement of weight rather than mass (to not blow up my brain) I am actually holding 1.02ish kg per 10 newtons? So my cars chasis has a weight of (1.02(bullet world gravity) * 6000) /10 so the relative actual weight of the car is 612kg aproximately so 0.67 tons? I am trying to calculate all this so I can figure out what calculations that are needed to make a ray vehicle class peform a power slide. I can do a hand break turn but loose my forward inertia due to grip vs weight I think before I manage to power slide very far at all. When my car loving brother/man of physics asked me for details on the cars various friction etc/MPH/Weight and various other details I could only tell him the weight was 600... somethings! so I decided to investigate.

Why is bullet world gravity different to earth gravity?
Dominik
Posts: 32
Joined: Fri Dec 19, 2008 2:51 pm

Re: Gravity 10 or 9.8? and weight calculations for dummies

Post by Dominik »

9.8 is pretty close to 10, so its just a rounded value.
Why do you want to use 9.8? The normallly used standard value is 9.81, even more precise is the global average of 9.80665m/s^2. ANd even this varies depending on the location. So it's always just an estimate. if you want a more precise one - why not simply set your desired gravity value yourself?