Interactions and Potential Energy

In summary, the conversation discusses the calculation of Usps and Ke for a bullet with a mass of 50g and a velocity of 300 m/s. It is suggested that the bullet will penetrate the creature due to Ke overcoming Usps. However, the discussion raises the question of whether the bullet's design (hollow point, sharp-nosed, or armor-piercing) will affect its ability to penetrate the creature's armor.
  • #1
CJoy
5
1
Homework Statement
The Cubarb parasite, having pursued Defiance Drake this far was not expecting either her sudden acrobatics, or to be shot by her futuristic slug throwing pistol. Nevertheless, Cubarbs have naturally flexible skin that afford them protection from projectiles, depending of course, on the amount of kinetic energy that the projectiles are carrying. The parasite's skin acts as a spring, with constant k=1.8 x 10^6 N/m, and as long as the deflection is less than 3cm (more than that and the skin breaks, and the parasite likely dies. If the bullet has a mass of 50g, and travels at 300 m/s, does the bullet bounce off the creature, or does it penetrate? How do you know?
Relevant Equations
Usp=1/2K(total s)^2
Ke=1/2mv^2
Esys=total Ke+total U+total Ethermal=Wext
Emech=total Ke+total U+ total Ethermal
Usps=1/2(1.8x10^6)(0.03)^2=810J
Ke=1/2mv^2=1/2(0.05)(300)^2=2250J
I don't know how to take it farther than this, or if this is the correct way to start the problem. If this is correct, would it be correct to assume that the bullet does penetrate the creature because Ke overcomes Usps?
 
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  • #2
CJoy said:
If the bullet has a mass of 50g, and travels at 300 m/s, does the bullet bounce off the creature, or does it penetrate?
Uh ... you think maybe it matters whether the bullet is a hollow point or sharp-nosed or armor-piercing ?
 
  • #3
CJoy said:
Usps=1/2(1.8x10^6)(0.03)^2=810J
Ke=1/2mv^2=1/2(0.05)(300)^2=2250J
I don't know how to take it farther than this, or if this is the correct way to start the problem. If this is correct, would it be correct to assume that the bullet does penetrate the creature because Ke overcomes Usps?
Yes, that is pretty clearly the intended approach. I agree with your calculations and your prediction for penetration.

As @phinds suggests, the armored skin specification in the problem statement does not seem very realistic or complete since it ignores the size of a projectile's pointed tip.
 

1. What are interactions and potential energy?

Interactions refer to the forces or actions between two or more objects, while potential energy is the energy that an object possesses due to its position or configuration.

2. How are interactions and potential energy related?

The interactions between objects can cause changes in their potential energy. For example, when two objects attract each other, their potential energy decreases, and when they repel each other, their potential energy increases.

3. What are some examples of interactions and potential energy in everyday life?

Some examples include a ball rolling down a hill (interaction between the ball and the gravitational force of the Earth), a magnet sticking to a refrigerator (interaction between the magnet and the magnetic field), and a spring bouncing up and down (interaction between the spring and the force applied to it).

4. How do interactions and potential energy affect the behavior of particles in a system?

The interactions between particles can determine the potential energy of the system, which in turn affects their movement and behavior. For example, particles with high potential energy are more likely to move and interact with each other compared to particles with low potential energy.

5. Can potential energy be converted into other forms of energy?

Yes, potential energy can be converted into other forms of energy, such as kinetic energy (energy of motion) or thermal energy (heat). This conversion can occur through interactions between objects or through a change in position or configuration of an object.

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