If one newton is approximately 98 kg per metre would the answer be 9 newtons ?. If so why don't I fall through the floor of an average house designed for loads of only 4 newtons ???
2007-03-20 02:43:48 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
Wow. The answers so far are so bad, I've had to give each one a thumbs down!
Right:
mass=100kg
force= mass x acceleration = 100*9.81 = 981N = 0.981kN
pressure = force/area = 981/0.11 = 8918N/m2 = 8.9kN/m2
Buildings are designed to BS6399-1, 1996, which states that buildings should be designed for a distributed load of 1.5kN/m2, and a point load of 1.4kN.
So the pressure exerted by you of 8.9kN/m2 should make the floor collapse, right? Wrong! If there were people covering every bit of available floorspace, then you would have 8.9kN/m2 for the whole floor, and it would fail. However, your feet aren't very big, and what you are exerting is very close to a point load, i.e. 0.98kN all acting in one place. As you can see, the floor is designed for a point load of 1.5kN, which is mroe than the pressure from your weight, and so the floor won't collapse.
2007-03-20 04:14:16 · answer #1 · answered by Steve-Bob 4 · 1⤊ 0⤋
The question is not how much pressure, rather how much force. Newtons second law of motion states that force is equa to mass multiplied by acceleration. Therefore the force is equal to the mass of the person (98kg) multiplied by the acceleration affect of gravity which is 9.81 metres per second. Therfore if the person was a dead weight he would exert 961N of force. However we must take into account the opposite force exerted by his legs which may reduce this by up to two thirds. Also most houses are designed for a load of 4KN which is kilo Newtons which is 4000 Newtons.
2007-03-20 03:13:47 · answer #2 · answered by Phillip H 1 · 0⤊ 2⤋
Steve Bo... is right.
I regularly use 1.5Kpa (1.5 kN/m2) for calcs.
His calcs are right to, although I would have accepted 10 instead of 9.81.
But I think we can make it simpler for you.
1.Your getting mixed up between N and kN.
1kg=9.81N
100kg=981N=0.981kN
2.Your allowable is pressure, not load.
I don't know where 4 comes from, I use 1.5Kn/m2.
0.981<1.5
or the other way
0.981kN / 0.11m2 = 8.91kN < 13.63kN = 1.5kN / 0.11m2
(edit)
Incidentally, I'm a temporary works specialist outside the UK. Which means my falsework requires 1.5kpa liveload. I wouldn't buy a house with so little. For the money they want these days I would expect 5kpa.
But then I wouldn't buy a wooden house either.
2007-03-21 02:07:29 · answer #3 · answered by Simon D 5 · 1⤊ 0⤋
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2016-10-02 10:50:03 · answer #4 · answered by ghalieh 3 · 0⤊ 0⤋
Pressure = Force / Area
Force = mg= 100kg * 9.8 m/s² = 980 N
»» P = 980 N / 0.11 m² = 8,909.10 N/m²
2007-03-22 01:55:22 · answer #5 · answered by M.M.D.C. 7 · 0⤊ 0⤋
100 kg/.11 sq meter = 980.665 newtons/sq meter = 980.665 pascals=20.48 psf which is a reasonable live load criteria.
2007-03-20 03:35:10 · answer #6 · answered by minorchord2000 6 · 1⤊ 1⤋
The force overall will be F = ma, or 100kg * 9.8m/s^2 = 980,000 Newtons. The Force per square foot will be F/sq.ft. = 980000/0.11 = 8.91MN or 8,909,090 N per square foot.
2007-03-20 03:53:58 · answer #7 · answered by joshnya68 4 · 0⤊ 2⤋
I think you had best ask Newton
2007-03-20 03:11:41 · answer #8 · answered by Anonymous · 0⤊ 1⤋
mass = 100kg
Force= 100xg=100x9.81=981KN
Area of his feet is 0.11sq m for two feet =0.22sq m
there fore the pressure is 981/0.22=4459=4.4Kp
2007-03-20 22:50:42 · answer #9 · answered by Simex 3 · 0⤊ 0⤋