Calculating Impact Energy of 7 Kg Dropped from 2 Meters

In summary, the impact energy is the total strain energy absorbed by the deforming body and is usually a large part of the kinetic energy of the object after falling. In the given scenario, the calculated kinetic energy of 137.34 Joules is pretty close to the impact energy. The standard definition of impact energy for a material is the total strain energy absorbed until fracture, but that is not relevant to this specific problem.
  • #1
kepler
29
0
Hi,

Supose I drop a body of 7 Kg from a height of 2 meters. Is the impact energy equal to:

E = m * g * h = 7 * 9.81 * 2 = 137,34 Joules ?

And if it is, is the kinetic energy equal to this ammount?

Kind regards,

Kepler
 
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  • #2
I'm not familiar with the the term "impact energy" in this context, but the energy that you calculated is the kinetic energy of the object after falling 2 meters.
 
  • #3
The impact energy is the total (elastic +plastic) strain energy absorbed by the deforming body. It is usually a large part of KE the body had before impact. Parts of the KE also go into heat and sound, but these fractions are usually small and are typically neglected.

So, the answer to the first question is: Yes, that's pretty close to the impact energy.

Note : The above is the definition of impact energy for an event. The standard definition of impact energy, however, is for a material. In that context, the impact energy is defined as the total strain energy absorbed until fracture (but that's not relevant to this specific problem).
 

What is the equation for calculating impact energy?

The equation for calculating impact energy is:
E = 1/2 * m * v^2
Where E is the impact energy, m is the mass of the object (in kilograms), and v is the velocity (in meters per second).

How do you calculate the impact energy of a 7 kg object dropped from 2 meters?

To calculate the impact energy of a 7 kg object dropped from 2 meters, we first need to calculate the velocity at impact. We can do this by using the equation v = √(2 * g * h), where g is the acceleration due to gravity (9.8 m/s^2) and h is the height (2 meters). Plugging in the values, we get v = √(2 * 9.8 * 2) = √39.2 = 6.26 m/s. Now, we can plug the mass and velocity into the equation for impact energy: E = 1/2 * 7 * (6.26)^2 = 137.5 joules.

Why is it important to calculate impact energy?

Calculating impact energy is important because it helps us understand the amount of force that an object will exert upon impact. This information is crucial in designing safety measures and protective gear, as well as predicting the damage that may occur in a collision or fall.

What are the units of impact energy?

The units of impact energy are joules (J), which is a unit of energy in the International System of Units (SI). However, sometimes impact energy is also expressed in terms of foot-pounds (ft-lb) or kilograms-force meters (kgf-m).

Is there a difference between impact energy and kinetic energy?

Yes, there is a difference between impact energy and kinetic energy. Impact energy is a measure of the energy an object has upon impact, while kinetic energy is a measure of the energy an object has due to its motion. However, impact energy and kinetic energy are related, as impact energy is a type of kinetic energy that is specifically associated with the motion of an object upon impact.

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