FULL REVIEW

Full Review: Simple Harmonic Motion — Algebra-Based

Review the essential ideas, relationships, and problem-solving tools for Simple Harmonic 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 is aligned to the approved Physics Sensei topic specification below. Use it to recover the topic structure, reinforce key decisions, and confirm readiness for the next study task.

RESOURCE: Independent Physics Sensei Unit Review

UNIT: Mechanics • Unit MEC-U09

TOPIC: Simple Harmonic Motion

COURSE LEVEL: Algebra-Based

BEST USED

✓ After reading the chapter

✓ 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 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

ALGEBRA-BASED
Use the force law before calculating.

A spring has k = 120 N/m and is stretched 0.050 m. Find the spring force, including sign if rightward displacement is positive.
Reveal Answer
F = −(120)(0.050) = −6.0 N.

Why it works: The minus sign is physical: the force opposes the displacement.

ACTIVITY 2

Recall Activity 2

ALGEBRA-BASED
Connect period, frequency, and angular frequency.

An oscillator has period 0.80 s. Find its frequency and angular frequency.
Reveal Answer
f = 1/T = 1.25 Hz and ω = 2πf ≈ 7.85 rad/s.

Why it works: Period is time per cycle; frequency is cycles per second; angular frequency measures phase advance in radians per second.

ACTIVITY 3

Recall Activity 3

ALGEBRA-BASED
Use total mechanical energy for an ideal spring oscillator.

For k = 200 N/m and amplitude A = 0.080 m, find the total mechanical energy.
Reveal Answer
E = ½kA² = 0.64 J.

Why it works: At a turning point v = 0 and all ideal mechanical energy is spring potential energy.

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?

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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

Restoring force and the SHM model

For an ideal spring, F = −kx. Combining this with F = ma gives a = −(k/m)x. The acceleration is zero at equilibrium, largest in magnitude at the turning points, and always directed toward equilibrium.

F = −kx; a = −(k/m)x; ω = √(k/m); T = 2π√(m/k)

Example: For m = 0.50 kg and k = 200 N/m, ω = 20 rad/s and T = 2π/20 ≈ 0.314 s.

Sensei Note: Do not call every back-and-forth motion SHM. The key test is whether the restoring force is approximately linear in displacement over the motion being modeled.

KEY CONCEPT 2

Amplitude, period, phase, displacement, velocity, and acceleration

A convenient model is x = A cos(ωt + φ), where φ sets the phase at t = 0. The maximum speed is Aω and the maximum acceleration is Aω². At equilibrium speed is largest; at the turning points speed is zero.

f = 1/T; ω = 2πf = 2π/T; x = A cos(ωt + φ); vₘₐₓ = Aω; aₘₐₓ = Aω²

Example: If A = 0.060 m and ω = 5.0 rad/s, vₘₐₓ = 0.30 m/s and aₘₐₓ = 1.5 m/s².

Sensei Note: Do not confuse amplitude with distance traveled in a cycle. One full cycle covers a path length 4A, while the amplitude is only A.

KEY CONCEPT 3

Energy, spring oscillators, and the simple pendulum

For a spring oscillator, E = ½kA² = ½mv² + ½kx². For a simple pendulum at small angle, T = 2π√(L/g). The ideal spring period depends on m and k, not amplitude; the small-angle pendulum period depends on L and g, not bob mass.

E = ½kA² = ½mv² + ½kx²; Tₛ = 2π√(m/k); Tₚ ≈ 2π√(L/g)

Example: A 0.90 m pendulum near small amplitude has T ≈ 2π√(0.90/9.8) ≈ 1.90 s.

Sensei Note: The simple-pendulum formula is a small-angle result. At large amplitude, the motion is periodic but not exactly simple harmonic and the period increases with amplitude.

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?

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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

Identify equilibrium, choose the positive direction, and apply the restoring-force model.

A 0.40 kg mass is attached to a 100 N/m spring. Find ω and T.
Reveal Answer
ω = √(100/0.40) = 15.8 rad/s; T = 2π/ω ≈ 0.397 s.

Why it works: The spring-mass period comes from T = 2π√(m/k).

PRACTICE 2

Guided Problem

Use the cycle relationships among x, v, a, T, f, and ω.

An oscillator has A = 0.050 m and f = 2.0 Hz. Find ω, vₘₐₓ, and aₘₐₓ.
Reveal Answer
ω = 4π ≈ 12.57 rad/s; vₘₐₓ ≈ 0.628 m/s; aₘₐₓ ≈ 7.90 m/s².

Why it works: Use vₘₐₓ = Aω and aₘₐₓ = Aω² after converting f to ω.

PRACTICE 3

Independent Problem

Use energy or the pendulum model, and state the assumptions that make the model valid.

A spring has k = 80 N/m and amplitude 0.10 m. Find total energy and the speed of a 0.50 kg mass at x = 0.060 m.
Reveal Answer
E = 0.40 J; U = 0.144 J; K = 0.256 J; v = √(2K/m) ≈ 1.01 m/s.

Why it works: Energy avoids solving for time or phase when position and speed are the target variables.

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?

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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

Restoring-force model check

Answer and justify in one sentence.

If k quadruples while m stays fixed, how do ω and T change?
Reveal Answer
ω doubles and T is halved.

Why it works: ω ∝ √k and T ∝ 1/√k.

QUICK CHECK 2

Cycle and phase check

Use the cycle, not memorized slogans.

If amplitude doubles but ω is unchanged, what happens to vₘₐₓ and aₘₐₓ?
Reveal Answer
Both double.

Why it works: Both maxima are directly proportional to A.

QUICK CHECK 3

Energy and pendulum model check

State the model assumption with the answer.

Does increasing the bob mass change the small-angle period of a simple pendulum?
Reveal Answer
No. T ≈ 2π√(L/g), independent of bob mass.

Why it works: Mass cancels from the ideal pendulum equation of motion.

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?

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Summary

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

KEY TAKEAWAY 1

Test the restoring law first

SHM requires a stable equilibrium and acceleration proportional to −displacement. For a spring, F = −kx and ω = √(k/m).

KEY TAKEAWAY 2

Read the cycle through phase relationships

Use ω = 2πf, x = A cos(ωt + φ), v = dx/dt, and a = −ω²x. At equilibrium speed is maximum; at turning points speed is zero.

KEY TAKEAWAY 3

Use energy and respect the small-angle limit

For an ideal spring, E = ½kA² is constant. A simple pendulum is approximately SHM only when sin θ ≈ θ is valid.

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?

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