# Center of mass of a tank (military vehicle)

1. May 25, 2012

### fondrika

1. The problem statement, all variables and given/known data
a toy which have a shape of tank (military vehicle) has a platform of 192mm long, 140mm wide, weight of 2075grams. The canon is 239mm long, 50mm wide, and weight of 400grams. the canon is on top of the platform and being assembled 58mm from the front side of platform.
where is the center of mass of it?
where is the center of mass if the canon rotate 90 degree?
where is the center of mass if the canon rotate 180 degree?

the canon is 58mm on top of the platform and the rest (239-58) 181mm is hanging in the air

3. The attempt at a solution
i really have no idea how to find it...

2. May 25, 2012

### tiny-tim

welcome to pf!

hi fondrika! welcome to pf!

what equations do you know for the centre of mass of a body made up of two parts?

3. May 25, 2012

### fondrika

i dont know an equations for CoM of a body made up of two parts...
i had just start learning center of mass.. but somehow i want to learn finding a center of mass of a body like that... but seems i dont know how... haha

4. May 25, 2012

### tiny-tim

what equations do you know for centre of mass?

5. May 25, 2012

### fondrika

x = (x1 m1 * x2 m2) / (m1+m2)

6. May 25, 2012

### tiny-tim

no, x = (x1 m1 + x2 m2) / (m1+m2)

ok, now apply that to the problem …

what do you get?

7. May 26, 2012

### fondrika

oh yeah.. a lil mistake on the equation.. haha
but which one is the x1 and x2? and there are no gap betwen each part...

8. May 26, 2012

### tiny-tim

(try using the X2 button just above the Reply box )

x1 and x2 are the centres of mass of the two parts

where are they?

(and you're going to need y1 y2 z1 and z2 also)

9. May 26, 2012

### fondrika

logically i now where the center of mass of each part. its just half of the wide and length isnt it?
is there any equation for to find the center of mass from a single part? or just use the the equation of X=(x1 m1 + x2 m2) / m1+m2 ?
if it is then the m1 and m2 will be the same? and which one is the x1 and x2?

btw thanks alot for helping me...

10. May 26, 2012

### tiny-tim

yes
yes, but each m is the mass (given in the question) of that particular part