# Advice 1: How to determine the stiffness coefficient

The coefficient shows how much force you need to apply to the body to elastically deform it to unit length. We are talking about elastic deformation, when the body after exposure to returns to previous form. To find this value, we need to deform the body, attaching a force or to measure the potential energy of deformation.
You will need
• calculator;
• - dynamometer;
• - the range.
Instruction
1
Attach to the body of the load cell and pull it, deforming the body. Power that will show the dynamometer, will be modulo equal to the force of elasticity, acting on the body. Find the coefficient using Hooke's law, which says that the force of elasticity is directly proportional to its elongation and directed in the direction opposite to deformation. Calculate the stiffness coefficient by dividing the value of the force F on the extension of the x body, which is measure with a ruler or tape measure k=F/x. To find the elongation of the deformed body, subtract the length of the body is deformed from its original length. The stiffness is measured in N/m.
2
If there is no dynamometer, hang to deformable body cargo known mass. Make sure that the body is elastically deformed and not destroyed. In this case, the weight of the load will be equal to the elastic force acting on the body, the coefficient for which you want to find, for example, springs. Calculate the stiffness coefficient by dividing the product of the mass m and the gravitational acceleration g≈9.81 m/S2 on the elongation of the body x, k=m•g/x. The elongation measure by the method proposed in the previous paragraph.
3
Example. Under the weight of 3 kg and a spring of length 20 cm was 26 cm, determine its stiffness. First, find the elongation of the spring in meters. To do this, the length of the elongated springs, subtract its length in normal condition x=26-20=6 cm=0.06 and m. Calculate the stiffness using the formula k=m•g/x=3•9,81/0,06≈500 N/m.
4
In the case where the known potential energy elastically deformed body, calculate its rigidity. For this additional measure its elongation. Stiffness will be equal to the doubled potential energy EP divided by the square of the elongation of the body x, k=2•Ep/x2. For example, if a ball is deformed by 2 cm and a potential energy of 4 j, then the stiffness k=2•4/0,022=20000 N/m.

# Advice 2: How to determine spring stiffness

Spring is a component of the car's suspension, which protected the car from irregularities in the road, but also provide the desired height of the body above the road, which greatly affects the handling of the vehicle, comfort and payload capacity. As a result of the tests for each vehicle select the optimum stiffness of the suspension springs under certain traffic conditions.
Instruction
1
If you experience "breakdowns" suspension spring is too soft. In such situations, the drivers become unstable in control. Ideally, the spring force must be equal to the value that prevents excessive body roll.
Stiffer springs require the cars prepared for racing. In different types of races using the same car involves the installation of springs with different stiffnessYu. Pay attention when passing any corners for body roll that, when properly selected springs should be no more than two or three degrees.
2
For the front and rear suspension pick spring stiffness pairs. However, it is not immediately possible to achieve the desired height of the suspension, because the spring sits and at some point may "get lost" that's really bad. This is due to lack of bearing capacity, even at full compression, but with the stiffnesss, providing the necessary height of the suspension. This is determined always easy: between the spring windings should be a gap of less than 4 mm.
3
Choose the springs so that when refilled the car the gap between the turns of the springs was slightly more than 6.5 mm. it is Desirable to set the soft springs, even though they will give a roll of the machine within acceptable limits. To use stiff springs, based on the opinion that they reduce the roll of the car, improving handling, as a rule, incorrect.
4
Check the stiffness of the spring by a product code or for applying labels or stamping paint). Also determine the stiffness of the springs using the hand pump, floor scales and measuring line in kilograms per centimeter.
On everyday scales fit a piece of wood (thickness 12 mm) square at the larger end of the spring, and the top is a spring. Then, on the upper end of the spring is placed a second piece of wood is measured length of the spring. With a press of the spring compress to a certain size (e.g. 30 mm) and take readings of the weights, thereby computing the stiffness.
Note
The pressure on the spring is measured according to the testimony of the weights, but this method of determining the stiffness of springs is dangerous as the spring can fly off at a sufficiently large distance.
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