Deformation of string from impact of an object with constant velocity

In summary, if a car with no acceleration, only velocity, hits a spring with a spring constant, the deformation in string will be calculated. The force exerted by the spring will be -kx.
  • #1
andrestander
4
0
If a car with no acceleration, only velocity, hits my spring with a spring constant K

What will be the deformation in string? How do I calculate the force from impact while acceleration is equal to 0?
 
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  • #2
Once the car hits the spring, it will have an acceleration, produced by the elastic force.
The force will increase as the deformation of the spring increases and will reach some maximum value.
Is this maximum value that you want to calculate?
 
  • #3
use work energy theorem.

See the kinetic energy of your car will be transferred to the spring.This energy stored in the the spring is its potential energy denoted by 0.5kx2.Here x is the deformation in spring.

so 0.5mv2=0.5kx2

m=mass of your car

from this you can calculate "x"
now
force exerted by the spring = -kx
 
  • #4
What if I have a simple beam structure and the object impacts in the middle of the beam? By how much the beam will deform and bend?
 
  • #5
andrestander said:
What if I have a simple beam structure and the object impacts in the middle of the beam? By how much the beam will deform and bend?
As a minimum, it depends on the material ( E = Young Modulus), and beam geometry (Area Moment of Inertia, I), and length between supports (L), impact speed, etc. Equivalent stiffness (k) of a simply supported beam subject to point loading at midpoint is 48EI/L^3, in units of force/length (N/m in SI).
 
  • #6
so 0.5mv^2=0.5kx^2

Where k is the equivalent stiffness matrix for the beam?
 
  • #7
andrestander said:
so 0.5mv^2=0.5kx^2

Where k is the equivalent stiffness matrix for the beam?

Yes, as I see it, but with a lot of assumptions, like the moving object is rigid and the beam remains within its elastic limit and obeys Hooke's Law when deforming. Also, if the moving object is is subject to gravity forces like for the case where it is moving straight down upon impact, then you must include its change in potential energy as well, that is, 0.5mv^2=0.5kx^2 -mgx.
 
  • #8
PhanthomJay said:
Yes, as I see it, but with a lot of assumptions, like the moving object is rigid and the beam remains within its elastic limit and obeys Hooke's Law when deforming. Also, if the moving object is is subject to gravity forces like for the case where it is moving straight down upon impact, then you must include its change in potential energy as well, that is, 0.5mv^2=0.5kx^2 -mgx.

Alright I'll do more searches and readings from there. Thanks a lot Jay. :)
 

1. What is the deformation of a string?

The deformation of a string refers to the change in its shape or position caused by an external force, such as the impact of an object.

2. How does an object with constant velocity affect the deformation of a string?

An object with constant velocity exerts a consistent amount of force on the string, resulting in a continuous and gradual deformation.

3. What factors influence the amount of deformation in a string?

The amount of deformation in a string is influenced by the mass and velocity of the impacting object, as well as the material and thickness of the string itself.

4. Can the deformation of a string be reversed?

In most cases, the deformation of a string can be reversed by removing the external force causing it and allowing the string to return to its original shape. However, in some cases, the deformation may be permanent due to the material properties of the string.

5. How is the deformation of a string measured?

The deformation of a string can be measured using various methods, such as using rulers or calipers to measure changes in length or using strain gauges to measure changes in tension. Other methods, such as high-speed cameras, can also be used to visually observe the deformation in real-time.

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