What is the speed of the dart as it leaves the toy?

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SUMMARY

The speed of a rubber dart, with a mass of 7.8 grams, as it leaves a toy is calculated using the principles of energy conservation. The dart is propelled by a spring with a force constant of 350 N/m, initially compressed by 4.5 cm. The elastic potential energy stored in the spring is entirely converted into kinetic energy of the dart. The final speed of the dart can be determined using the equations Ee = Ek and Ee = 1/2 k x^2, leading to a definitive calculation of its exit velocity.

PREREQUISITES
  • Understanding of energy conservation principles
  • Familiarity with Hooke's Law and spring constants
  • Knowledge of kinetic energy equations
  • Basic algebra for solving equations
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  • Calculate the speed of the dart using the formula v = sqrt((k * x^2) / m)
  • Explore the effects of varying spring constants on projectile speed
  • Investigate energy loss factors in real-world applications of spring-powered toys
  • Learn about the relationship between mass and velocity in projectile motion
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Students studying physics, educators teaching mechanics, and hobbyists interested in the physics of toy projectiles will benefit from this discussion.

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Homework Statement



2. 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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In the equation for spring energy, x represents the distance the spring is compressed.
 
jbjohnybaker said:

Homework Statement



2. 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 ??



You got the formulas correctly
E= kinetic + potential
Einitial = E final
1/2 kx^2 + 1/2 mv^2 = 1/2 mv^2 + 1/2 kx^2

1/2 * 3.5 x 10^2 * .04m + 0 = 1/2 *.0078 kg v^2 +0

now just solve for V.
I think you just missed the information that tells you the compression (x)
 

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