FULL REVIEW

Full Review: Uniform Circular Motion — Algebra-Based

Review the essential ideas, relationships, and problem-solving tools for Uniform Circular Motion.

TIME

45–60 minutes

BEST FOR

A complete topic review

FINISH WITH

A readiness check

After this full review, you'll be able to...

recall the essential ideas, apply them to representative problems, and determine what to study next.

Choose how you want to review

Topic Alignment

This bundle follows the approved independent Physics Sensei unit specification. Use it to reinforce key concepts, prepare for coursework, or review before an assessment.

 RESOURCE: Independent Physics Sensei Unit Review

UNIT: Mechanics • MEC-U16

TOPIC: Uniform Circular Motion

COURSE LEVEL: Algebra-Based

BEST USED

✓ After studying the unit

✓ Before starting homework

✓ Before a quiz or exam

Physics Sensei is an independent educational resource built from the approved Physics Sensei unit specification.

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 45-60 minutes.

Warm-Up Check

Activate prior knowledge.

Core Concepts

Review the essential ideas.

Guided Practice

Apply what you learned.

Confidence Check

Confirm your understanding.

Summary

Review the key ideas.

Next Step

Continue your learning.

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

Recall Activity 1

Sketch velocity and acceleration directions.

An object moves counterclockwise. At the rightmost point, give the directions of velocity and centripetal acceleration.
Reveal Answers
Velocity is upward; acceleration is left, toward the center.

Why it works: Velocity is tangent to the path; centripetal acceleration points inward.

ACTIVITY 2

Recall Activity 2

Use v=2πr/T.

An object moves on a circle of radius 2.5 m with period 4.0 s. Find its speed.
Reveal Answers
v=2π(2.5)/4.0=3.93 m/s.

Why it works: One revolution covers 2πr in one period T.

ACTIVITY 3

Recall Activity 3

Apply the radial form of Newton’s second law.

A 1200 kg car travels at 15 m/s on a flat curve of radius 50 m. Find the required inward net force.
Reveal Answers
Fᵣ=mv²/r=5400 N inward.

Why it works: The real horizontal forces must combine to produce mv²/r toward the center.

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?

← View Review Map

Core Concepts

Let's rebuild the key ideas one step at a time. Focus on understanding the relationships before worrying about solving problems.

KEY CONCEPT 1

Circular kinematics: period, frequency, angular speed, and linear speed 1

Use f=1/T, ω=2π/T=2πf, and v=ωr=2πr/T. Select the equation that connects the known quantities instead of using every relation automatically.

f=1/T; ω=2π/T=2πf; v=ωr=2πr/T.

For r=2.5 m and T=4.0 s, v=3.93 m/s.

Linear speed and angular speed are related but not identical. Points at different radii can share the same angular speed while having different linear speeds.

KEY CONCEPT 2

Centripetal acceleration: changing direction at constant speed 2

The magnitude is ac=v²/r=ω²r. At fixed radius, doubling speed makes the acceleration four times larger. At fixed speed, increasing radius decreases the acceleration.

ac=v²/r=ω²r.

For v=3.93 m/s and r=2.5 m, ac=6.18 m/s².

A statement about how acceleration changes with radius is incomplete unless you also state what is held constant: speed, angular speed, or period.

KEY CONCEPT 3

Radial force modeling: the inward net force 3

Draw the free-body diagram first. Then use ΣFᵣ=mv²/r, taking inward as the positive radial direction if convenient. Do not add a separate centripetal-force arrow.

ΣFᵣ=mv²/r=mω²r.

For a 1200 kg car at 15 m/s on a 50 m curve, the required inward net force is 5400 N.

“Centripetal” describes the required inward net-force direction. It is not the name of an additional physical interaction.

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?

← View Review Map

Guided Practice

Now it's time to apply what you've reviewed.

Work through each activity in order. The examples become gradually more challenging, and each one prepares you for the final readiness check.

PRACTICE 1

Worked Example

Connect period, angular speed, and linear speed; keep units visible.

A platform has radius 1.8 m and frequency 0.50 Hz. Find ω and the speed at the edge.
Reveal Answers
ω=2πf=3.14 rad/s; v=ωr=5.65 m/s.

Why it works: Frequency sets angular speed; multiplying by radius gives linear speed.

PRACTICE 2

Guided Problem

Draw the free-body diagram, identify the inward direction, and then apply the radial equation.

A 1200 kg car travels at 15 m/s on a 50 m flat curve. Find the required friction force and the minimum μs.
Reveal Answers
Ff=5400 N inward; μs=v²/(rg)=0.459.

Why it works: Static friction supplies mv²/r; μsN is the maximum available static friction, with N=mg on a flat road.

PRACTICE 3

Independent Problem

Separate vertical balance from radial acceleration.

A 0.50 kg mass on a 1.5 m string moves at 30° from vertical. Find the circle radius, tension, speed, and angular speed.
Reveal Answers
r=0.75 m; T=5.66 N; v=2.06 m/s; ω=2.75 rad/s.

Why it works: Vertical acceleration is zero while radial acceleration is v²/r. Combining the component equations gives tanθ=v²/(rg).

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?

← View Review Map

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

Direction check

Answer without drawing a separate centripetal-force arrow.

At the rightmost point of counterclockwise motion, where do v and ac point?
Reveal Answers
Velocity upward; acceleration left.

Why it works: Velocity is tangent to the path; centripetal acceleration is radial and inward.

QUICK CHECK 2

Scaling check

State what is held constant before giving the factor.

At fixed speed, what happens to ac if radius doubles?
Reveal Answers
It becomes half as large.

Why it works: Use ac=v²/r when speed is controlled and ac=ω²r when angular speed is controlled.

QUICK CHECK 3

Force-model check

Name the real interaction and the radial equation.

Should a car-on-a-flat-curve free-body diagram contain both friction and a separate centripetal force?
Reveal Answers
No. Static friction is the real force that can supply the inward net force.

Why it works: Centripetal force is not an additional interaction; it is the inward net-force requirement.

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?

← View Review Map

Summary

Before moving on, take one final look at the most important ideas from this review.

KEY TAKEAWAY 1

Connect T, f, ω, and v before calculating

One revolution is 2π radians and a distance 2πr. Use f=1/T, ω=2π/T, and v=ωr to translate between cycle, angular, and linear descriptions.

KEY TAKEAWAY 2

Velocity is tangent; acceleration is inward

Constant speed can coexist with nonzero acceleration because velocity direction changes. Use ac=v²/r=ω²r and always identify the center first.

KEY TAKEAWAY 3

Model the real forces, then impose the radial requirement

Draw the free-body diagram with actual interactions. Their inward components must satisfy ΣFᵣ=mv²/r; never add a duplicate “centripetal force.”

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?

← View Review Map

Next Step

Great work!

You've completed this review. Choose the next resource that best matches how confident you feel.

I'm Still Unsure

Review the key ideas and examples again.

Review Again →

I Need More Practice

Continue with additional practice for this topic.

Go to Practice →

I'm Ready

Continue to the next recommended resource.

Continue →

Continue reviewing with these companion resources