|
|
|
|
|
|
Welcome to the Australian Ford Forums forum. You are currently viewing our boards as a guest which gives you limited access to view most discussions and inserts advertising. By joining our free community you will have access to post topics, communicate privately with other members, respond to polls, upload content and access many other special features without post based advertising banners. Registration is simple and absolutely free so please, join our community today! If you have any problems with the registration process or your account login, please contact us. Please Note: All new registrations go through a manual approval queue to keep spammers out. This is checked twice each day so there will be a delay before your registration is activated. |
|
|||||||
| The Bar For non Automotive Related Chat |
 |
|
|
Thread Tools | Display Modes |
15-02-2015, 07:06 PM
|
#1 | ||
|
BANNED
Join Date: Jul 2012
Posts: 2,886
|
Trying to settle an argument between a few boys.
I have a 500kg rock to move. How much does it weigh when underwater compared to out of water? Is it 500kg minus the weight of the water it displaces? Is it the weight of the water it displaces? We all agree that it weighs less. does anyone know for sure? TIA |
||
|
|
|
15-02-2015, 07:15 PM
|
#2 | ||
|
Donating Member
 
Join Date: Jan 2005
Location: Morayfield
Posts: 28,191
  
|
Archimedes principal. It will weigh less according to the weigh of water it displaces .
Mass remains constant.
__________________
I love Holdens.... |
||
|
|
|
|
15-02-2015, 07:22 PM
|
#3 | |||
|
Former BTIKD
 
Join Date: Mar 2005
Location: Sunny Downtown Wagga Wagga. NSW.
Posts: 53,197
|
Quote:
__________________
Dying at your job is natures way of saying that you're in the wrong line of work.
|
|||
|
|
|
|
15-02-2015, 07:23 PM
|
#4 | ||
|
FF.Com.Au Hardcore
Join Date: Jun 2010
Posts: 700
|
It will weigh more, because it's the weight of the rock plus the weight of all the water above the rock.
|
||
|
|
|
|
15-02-2015, 07:52 PM
|
#6 | |||
|
If it ain't broke........
 Join Date: Dec 2007
Location: Sunshine Coast Qld
Posts: 18,812
|
Quote:
__________________
Visitors welcome Relatives by appointment only |
|||
|
|
|
| 3 users like this post: |
|
15-02-2015, 08:40 PM
|
#8 | ||
|
Peter Car
Join Date: Dec 2004
Location: geelong
Posts: 23,145
|
A 500kg rock is still 500kg no matter where it is?
|
||
|
|
|
| This user likes this post: |
|
15-02-2015, 08:55 PM
|
#9 | ||
|
Thailand Specials
Join Date: Aug 2009
Location: Centrefold Lounge
Posts: 49,629
|
I stopped taking physics after year 11 for a damn good reason.
|
||
|
|
|
| 4 users like this post: |
|
15-02-2015, 08:59 PM
|
#10 | ||
|
FF.Com.Au Hardcore
Join Date: Apr 2013
Posts: 3,318
|
Does that principle apply to the Dead Sea, which has an extremely high salinity level?
Closest thing I've ever come to science is trying to sabotage my brothers chemistry kit. |
||
|
|
|
|
15-02-2015, 09:08 PM
|
#11 | ||
|
Donating Member
Join Date: Oct 2013
Location: Wellington NZ
Posts: 11,423
|
Upthrust = apparent loss of weight of object = weight in air - weight in liquid. The upthrust is altered by density of the water i.e. saltwater increases the amount displaced.
|
||
|
|
|
|
15-02-2015, 09:19 PM
|
#12 | ||
|
FF.Com.Au Hardcore
Join Date: Dec 2004
Location: Canberra Region
Posts: 9,022
|
What altitude?
__________________
2016 FGX XR8 Sprint, 6speed manual, Kinetic Blue #170 2004 BA wagon RTV project. 1998 EL XR8, Auto, Hot Chilli Red 1993 ED XR6, 5speed, Polynesian Green. 1 of 329. Retired 1968 XT Falcon 500 wagon, 3 on the tree, 3.6L. Patina project. |
||
|
|
|
|
15-02-2015, 09:46 PM
|
#13 | ||
|
Fat 460
Join Date: Jun 2006
Location: Perth
Posts: 2,649
|
If it's Pumice stone it will float.
__________________
1963 1/2 Galaxie Fastback. Rangoon Red. 427/4 speed. 1970 Galaxie Sportsroof. Matt black/purple scallops. 460/C6. 1972 XA GT Sedan. Monza Red. 351C/4 speed. 2003 BA XR8 Ute. Blood Orange. 5.4/5 speed. 2006 Territory Turbo. Silhouette. 4.0/6 speed auto. |
||
|
|
|
| This user likes this post: |
|
15-02-2015, 09:56 PM
|
#14 | ||
|
FF.Com.Au Hardcore
Join Date: Jul 2006
Posts: 7,331
|
Wouldnt a denser, smaller rock displace less water? Assuming neither will float or anything stupid like that?
|
||
|
|
|
|
15-02-2015, 10:00 PM
|
#15 | ||
|
Boss 335
Join Date: Jan 2006
Posts: 4,330
|
asking google 'how heavy is a rock' returns:
118 kg Dwayne Johnson, Weight |
||
|
|
|
| 10 users like this post: |
|
15-02-2015, 10:08 PM
|
#16 | ||
|
BANNED
Join Date: Jul 2012
Posts: 2,886
|
ROFL some interesting answers here...
sounds like a cubic metre of concrete (2.4T) weighs 1.4T under water. cheers |
||
|
|
|
|
15-02-2015, 10:34 PM
|
#18 | ||
|
FF.Com.Au Hardcore
Join Date: Dec 2004
Location: Brisbane
Posts: 1,198
|
Exact answer...
=1000 kg/m^3 V = m / ρ V = [500kg] / [1000 kg/m^3] = 0.5 m^3 Volume of displaced water = 0.5m^3
__________________
FROZEN WHITE XR5 TURBO & MOONDUST SILVER XR5 TURBO PREVIOUS RIDES AU3 VENOM RED XR8, 19" SILVER ARGENTS, REBEL BODY KIT & 6/4 BREMBOS MARS RED FG MK2 XR6 ECOLPI, SILVER ARGENT 19" RIMS & TINT BLOOD ORANGE BA GTP, QUAD EXHAUST, SUNROOF, CHIPPED, SS CAI, 320KW NAROOMA BLUE AU3 HERROD XR8- SS CAI, TS RIMS, 6/4 BREMBOS, TWIN SPOILER, REBEL BODY KIT & TUNED BY ELITE VENOM GTP, HERROD EXHAUST, DVD PLAYER, WINDOW TINT, SS CAI, STEALTH VENOM AU11 TE50, HERROD LOWERED, HEADERS AND EXHAUST [SIGPIC][/SIGPIC]
|
||
|
|
|
| This user likes this post: |
|
16-02-2015, 12:05 AM
|
#19 | |||
|
FF.Com.Au Hardcore
Join Date: Jan 2005
Posts: 4,167
|
Quote:
__________________
igodabigblackshinycar and I relented and allowed a BMW into the garage. 
|
|||
|
|
|
|
16-02-2015, 07:31 AM
|
#20 | ||
|
When in doubt, GAS IT!!
Join Date: Sep 2006
Location: Lower Eyre Peninsula, SA
Posts: 3,018
|
If it's static I reckon it'd weigh the same 500kg. If you try to lift it, it would take more force or energy to move it as you have to displace to water above it as you lift so it would effectively make it appear heavier than it's 500kg.
Take a brick, suspend it from a set of digital fish scales and take a reading. Then suspend the brick in a bucket of water on the scales and read it again. My money is on it still reading the same once it settles.
__________________
. HERS- BFIII Wagon Gold, alloys, dual fuel, bullbar, big tow pack, trans cooler, fully rebuilt HD suspension, Clarion, alarmed, full 2 1/2" sports system, mint body MINE- AUII Forte Meteorite, dual fuel but otherwise bog stock. MINE- AUII Fairlane Sportsman Liquid Silver over meteorite,HIDs', Airhog, Eagle Leads, dual fuel, custom rear springs, BA slotted discs + a second one for spares . |
||
|
|
|
|
16-02-2015, 07:32 AM
|
#21 | ||
|
The one and only
Join Date: Dec 2004
Location: Carrum Downs, Victoria
Posts: 9,053
|
Rock isn't as heavy as metal \m/
__________________
1992 DC LTDHO 360rwkw built by me Tuned by CVE Performance Going of the rails on a crazy train Other cars include Dynamic ED Sprint, Dynamic DL LTD, Sparkling Burgundy DL LTD, Yellow, Red & Blue XB sedan & Black XB Coupe
|
||
|
|
|
| 10 users like this post: |
|
16-02-2015, 08:22 AM
|
#22 | ||
|
FF.Com.Au Hardcore
Join Date: Jun 2011
Location: Pt Lincoln far side South Oz
Posts: 5,890
|
I need a strong drink
__________________
Dont p i s s off older people. At our age the term Life in Prison is not a deterrent |
||
|
|
|
|
16-02-2015, 09:23 AM
|
#24 | ||
|
Former BTIKD
Join Date: Mar 2005
Location: Sunny Downtown Wagga Wagga. NSW.
Posts: 53,197
|
cs123 got it on the first reply, this should explain it a little .....
http://physics.weber.edu/carroll/arc.../principle.htm 
__________________
Dying at your job is natures way of saying that you're in the wrong line of work.
|
||
|
|
|
| 5 users like this post: |
|
16-02-2015, 09:37 AM
|
#25 | |||
|
FF.Com.Au Hardcore
Join Date: Apr 2012
Posts: 980
|
Quote:
except the density of rock is more likely to be 2,500kg.m^-3. Without knowing the type of rock, this is agood enough approximation. Malazn mafia is on to something, though, get Dwayne to move it for you!! Steve |
|||
|
|
|
|
16-02-2015, 10:42 AM
|
#26 | ||
|
Regular Member
Join Date: Jun 2012
Posts: 126
|
***WARNING! SCIENCE CONTENT!***
Discounting any inherent buoyancy in the object that would create a notable difference in behaviour between air and water: The mass is constant, with the weight depending on the gravitational force in the rock's environment, ie, it would weigh heaps more on Jupiter than on Earth. On earth, gravity is 9.807m/s^2, so a 500kg rock (or anything else) would require 4903.325 Newtons (N) to lift it, regardless of whether it is water or air. The easiest way to think about this is lifting it off the ground, or the seabed while standing on the solid surface. HOWEVER! if you were using a helicopter versus a submarine, this were it might become 'easier' or 'harder', despite the required force being exactly the same. The only difference is that water is a denser medium, so it will be easier to push against to get up to your ~5000N. The amount of water (by weight) displaced is equal to the weight of the object - if the object floats. If the object sinks, the amount of water displaced (by volume) is equal to the volume of the sunken object. eg. a 2000kg boat will displace 2000kg (2000L) of water, but a cannonball with a volume of 1L, will only displace 1L of water, regardless of weight. |
||
|
|
|
|
16-02-2015, 10:46 AM
|
#27 | ||
|
Isn't it obvious?
Join Date: Nov 2009
Location: in a world of idiots
Posts: 5,383
|
my brain thingy hurts
__________________
08 Strike G6E T. 10 Ergo G6E Sept 75 XB Falcon in mushroom beige, 3 on the tree 200cid for sale, offers in the teens |
||
|
|
|
| 3 users like this post: |
|
16-02-2015, 08:02 PM
|
#29 | ||
|
Peter Car
Join Date: Dec 2004
Location: geelong
Posts: 23,145
|
Beat it nerds. Your fancy science ain't welcome here
|
||
|
|
|
| 3 users like this post: |
|
16-02-2015, 11:29 PM
|
#30 | ||
|
Formerly ST170ish
Join Date: Jan 2005
Location: Down south
Posts: 1,674
|
What if I hit your rock and break it
__________________
My bad attitude escalates in direct proportion to the amount of stupidity I am presented with!!! 
|
||
|
|
|
How heavy is a rock?
Linear Mode
