FOCUSED REVIEW
Focused Review — Work and the Work–Energy Theorem — Foundational
Reinforce the highest-leverage ideas and representative problem-solving tools for Work and the Work–Energy Theorem.
TIME
Approximately 15 minutes
BEST FOR
Targeted reinforcement
FINISH WITH
A readiness check
After this focused review, you'll be able to...
reinforce the key relationships, apply them to representative problems, and identify what still needs work.
Choose how you want to review
Course Alignment
This Physics Sensei Topic Review is an independent learning resource. Use it to reinforce key concepts, prepare for homework, or review before a quiz or exam.
Related Unit Review: If you need to review the complete unit material, review Work, Energy, and Power here →
RESOURCE: Physics Sensei Topic Review | TOPIC ID: MEC-U06-T01 | TOPIC: Work and the Work–Energy Theorem | PARENT UNIT: MEC-U06 — Work, Energy, and Power | COURSE LEVEL: Foundational
BEST USED ✓ After learning the topic ✓ Before starting homework ✓ Before a quiz or exam
Your Review Plan
Complete these six stages in order. Each stage builds on the previous one and prepares you for the final readiness check.
6 Stages • Approximately 15 minutes.
Warm-Up Check
Before you begin, take a moment to see what you already remember. Do not worry about getting everything right. This is only a starting point.
ACTIVITY 1
Key Ideas
Answer before revealing the response.
In one sentence, describe when a force does positive work.
Reveal Answers
Positive work occurs when the force has a component in the direction of displacement.
Why it works: A force component along displacement transfers energy to the object.
ACTIVITY 2
Common Mistakes
Answer before revealing the response.
A force acts on an object but the object does not move. How much work is done by that force?
Reveal Answers
0 J. Without displacement, this force transfers no energy by work.
Why it works: Work requires displacement through the force’s line of action.
ACTIVITY 3
Quick Application
Answer before revealing the response.
A 12 N force pushes a cart 4 m in the direction of motion. Find the work done.
Reveal Answers
48 J. For a parallel force, work is force times displacement: 12 × 4 = 48 J.
Why it works: Parallel force and displacement make the work equal to force times distance.
Ready to strengthen your understanding?
You've refreshed what you already know. Next, you'll reinforce the essential concepts that will help you solve problems with confidence. Need to see the learning path again?
Core Concepts
Reinforce the two highest-leverage relationships, then use them in representative situations.
KEY CONCEPT 1
Work and the Direction of Force
Work depends on the part of a force that acts along the displacement. A force in the direction of motion does positive work; a force opposite the motion does negative work.
W = Fd
Example: A 20 N forward force over 2 m does +40 J of work when it is parallel to the motion.
Sensei note: A force can be present without doing work if there is no displacement in its direction.
KEY CONCEPT 2
Net Work Changes Kinetic Energy
The total work done by all forces changes an object’s kinetic energy. Positive net work increases kinetic energy; negative net work decreases it.
Wnet = ΔK
Example: If the net work on a cart is +15 J, its kinetic energy increases by 15 J.
Sensei note: The work–energy theorem uses net work, not the work of only one selected force.
Ready to apply these ideas?
You've reinforced the essential concepts. Now it's time to put them into practice by working through guided examples and building your problem-solving confidence. Need a quick reminder?
Guided Practice
Apply the reinforced ideas to two representative situations, then use the strategy card to check your setup.
PRACTICE 1
Guided Example
Use the force and displacement to calculate the work, then interpret its sign.
A 15 N horizontal push moves a crate 5 m forward. Show the calculation and state whether the work adds or removes energy.
Reveal Answers
75 J, positive. The push transfers 75 J of energy to the crate.
Why it works: The applied force is parallel to the displacement, so the work is positive.
PRACTICE 2
Independent Check
Use the work–energy theorem to determine the change in kinetic energy.
The net work on a cart is -24 J. If its initial kinetic energy is 60 J, find its final kinetic energy.
Reveal Answers
36 J. The kinetic energy changes by -24 J: 60 J - 24 J = 36 J.
Why it works: Net work equals the change in kinetic energy.
Ready to check your understanding?
You've practiced the essential skills with guidance. Now it's time to solve a few short problems on your own and confirm you're ready to move forward. Need a quick reminder?
Confidence Check
You've rebuilt the key ideas and practiced them with guidance. Now try these short questions on your own to check your understanding before moving on.
QUICK CHECK 1
Sign of Work
Solve independently before checking the solution.
A braking force acts opposite a car’s displacement. Is the work by the braking force positive, negative, or zero?
Reveal Answers
Negative. The braking force points opposite the displacement.
Why it works: Opposite force and displacement give negative work.
QUICK CHECK 2
Kinetic-Energy Change
Solve independently before checking the solution.
A moving object has 40 J of kinetic energy. The net work on it is +25 J. What is its final kinetic energy?
Reveal Answers
65 J. The object gains 25 J of kinetic energy.
Why it works: Positive net work increases kinetic energy by the same amount.
How did it go?
You've checked your understanding. Take one final look at the essential ideas before deciding what to do next. Need a quick reminder?
Summary
Before moving on, take one final look at the essential ideas you’ll want to remember.
KEY TAKEAWAY 1
Work Has a Sign
The sign of work tells whether a force adds energy to or removes energy from the object.
KEY TAKEAWAY 2
Net Work Tracks Kinetic Energy
Net work equals the change in kinetic energy, so it connects forces and motion through energy.
MY ONE-SENTENCE SUMMARY
In my own words, the most important idea is:
____________________________________________
Ready for your next step?
You've reviewed the essential ideas one last time. Now choose the resource that best matches how confident you feel. Need a quick reminder?
Next Step
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