Mechanics: Work and Energy

Work and Energy: Audio Guided Solution

Problem Set WE10, Question 2:

A car is moving across a level highway with a kinetic energy of 137646 Joules. The brakes are applied and the wheels become locked as the 875-kg car slows to a stop over 5.56 seconds. Determine the work done upon the car. Enter the appropriate + or – sign.
 

 

 

Audio Guided Solution

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

KE_i + PE_i + W_nc = KE_f + PE_f

 

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.

• Situations Involving External Forces

 

Watch It!

Try our YouTube video on the topic of ...

• External Energy Transfer