Mechanics: Work and Energy

Work and Energy: Audio Guided Solution

Problem Set WE7, Question 7:

A spring has a force constant of 420 N/m. When the spring is stretched 4.84 cm from the equilibrium position, then what amount of energy (in Joules) is stored in the spring?

 

 

Audio Guided Solution

 

Use the equations below to solve this problem. Cancel terms, substitute and solve.

KE_i + PE_i + W_nc = KE_f + PE_f

0.5•m•v_i² + m•g•h _i + 0.5•k•x_i² + F•d•cos Θ = 0.5•m•v_f² + m•g•h _f + 0.5•k•x_f²

 

Habits of an Effective Problem Solver

• Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
• Identify the known and unknown quantities in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., v_o = 0 m/s; a = 4.2 m/s/s; v_f = 22.9 m/s; d = ???.
• Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
• Identify the appropriate formula(s) to use.
• Perform substitutions and algebraic manipulations in order to solve for the unknown quantity

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Read About It!

Get more information on the topic of Work and Energy at The Physics Classroom Tutorial.

• Potential Energy

 

 

Watch It!

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• Potential Energy