Help with elastic potential energy

In summary, a child's toy shoots a rubber dart with mass 7.8g using a compressed spring with force constant 3.5 x 10^2 N/m. The spring is initially compressed 4.5cm and all the elastic potential energy is converted into kinetic energy of the dart. The speed of the dart as it leaves the toy can be calculated by equating the elastic potential energy to the kinetic energy and solving for v. The equation for v is v = √(k/m)x, where k is the spring constant, m is the mass of the dart, and x is the initial compression of the spring. Plugging in the given values, we can compute the speed of the dart.
  • #1
jbjohnybaker
19
0

Homework Statement



A child's toy shoots a rubber dart of mass 7.8g, using a compressed spring with a force constant of 3.5 x 10^2 N/m. The spring is initially compressed 4.5cm. All the elastic potential energy is converted into kinetic energy of the dart.
What is the speed of the dart as it leaves the toy?


Homework Equations


Ee = Ek
Ee = 1/2 k x^2
Ek = 1/2 mv^2

The Attempt at a Solution


Ee = Ek
1/2 (3.5 x10^2)(?) = 1/2 (.0078)v^2 ??]
 
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  • #2


jbjohnybaker said:

Homework Statement



A child's toy shoots a rubber dart of mass 7.8g, using a compressed spring with a force constant of 3.5 x 10^2 N/m. The spring is initially compressed 4.5cm. All the elastic potential energy is converted into kinetic energy of the dart.
What is the speed of the dart as it leaves the toy?


Homework Equations


Ee = Ek
Ee = 1/2 k x^2
Ek = 1/2 mv^2

The Attempt at a Solution


Ee = Ek
1/2 (3.5 x10^2)(?) = 1/2 (.0078)v^2 ??]
How much is the spring compressed?

http://www.physics247.com/physics-tutorial/spring-potential-energy.shtml"
 
Last edited by a moderator:
  • #3


equating Ee to Ek is indeed the right way to go. I suggest writing that equation in symbols (not yet plugging in the numbers) and then solving for v.
You'll get an expression for v in terms of k (spring constant), m (mass of the dart) and x (initial compression of the spring), all of which are given.
Then you simply plug in the given values and compute the value for v.

Alex
 

Related to Help with elastic potential energy

What is elastic potential energy?

Elastic potential energy is the energy stored in an object when it is stretched or compressed. It is a form of potential energy that can be converted into kinetic energy when the object returns to its original shape.

How is elastic potential energy calculated?

The formula for calculating elastic potential energy is Ee = 1/2kx^2, where Ee is the elastic potential energy, k is the spring constant, and x is the displacement from the equilibrium position.

What are some examples of objects with elastic potential energy?

Examples of objects with elastic potential energy include springs, rubber bands, trampolines, and bungee cords. These objects can store energy when they are stretched or compressed and release it when they return to their original shape.

How does elastic potential energy relate to Hooke's law?

Hooke's law states that the force exerted by a spring is directly proportional to the amount it is stretched or compressed. This force is also equal to the negative of the spring constant times the displacement. This relationship is important in calculating elastic potential energy.

What are some real-life applications of elastic potential energy?

Elastic potential energy has many practical applications in everyday life. It is used in the suspension systems of vehicles, in shock absorbers, and in elastic materials used for cushioning. It is also crucial in the design of bridges, buildings, and other structures that need to withstand external forces.

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