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Science lesson plan · 9th grade (Year 10 in England) · 60 minutes

Kinetic and gravitational potential energy

Energy

CCSS NGSS.MS-PS3-1CCSS NGSS.MS-PS3-2CCSS NGSS.HS-PS3-1CCSS NGSS.HS-PS3-2England: KS4 Combined Science: Energy

Objective and success criteria

Students will: Kinetic and gravitational potential energy.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Conservation of energy and wasted energy; Mass and weight (W = mg)

Leads to: Work done, power and energy costs; Energy stored in a stretched spring (E = ½ k e²); Use energy conservation to find speeds and heights

Materials: Wind-up toys or a pendulum, Energy transfer diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 6 min

  • Quick retrieval from earlier learning (Conservation of energy and wasted energy; Mass and weight (W = mg)). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. A speaker is supplied with 1200 J of energy. It transfers 900 J usefully. How much energy is wasted, in J? → 300 JPrompt: Energy is conserved: input = useful output + wasted output.
  2. What is the weight of a 50 kg object on Earth? Use g = 9.8 N/kg. → 490 NPrompt: weight = mass × gravitational field strength (W = m g)
  3. A ball is dropped and each bounce is lower. Where did the energy go? (It was destroyed / It was transferred to the surroundings as heat and sound / Gravity took it / It went into the ball's mass) → It was transferred to the surroundings as heat and soundPrompt: Energy is never destroyed.

Hook · 6 min

  • Wind up a toy or stretch an elastic band and ask where the energy goes.
  • Share the objective: Kinetic and gravitational potential energy. Read the success criteria together.

I do: model it · 12 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: What is the kinetic energy of a 60 kg object moving at 5 m/s? Use Eâ‚– = ½ m v².
  • Step 1: Eâ‚– = ½ × 60 × 5²
  • Step 2: = 0.5 × 60 × 25 = 750
  • Step 3: So the answer is: 750 J
  • Answer: 750 J
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 12 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. What is the kinetic energy of a 1000 kg object moving at 20 m/s? Use Eₖ = ½ m v². → 200000 JPrompt: Square the speed first.
  2. An object of mass 50 kg is lifted 3 m. How much gravitational potential energy does it gain? Use Eₚ = m g h with g = 9.8 N/kg. → 1470 JPrompt: Multiply mass, gravitational field strength and height.

You do: independent practice · 17 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A ball is dropped from 45 m. Ignoring air resistance, all its gravitational potential energy becomes kinetic energy. How fast is it moving just before it lands, in m/s? Use g = 10 N/kg. → 30 m/sPrompt: Set m g h = ½ m v². The mass cancels.
  2. An object of mass 2 kg is lifted 2 m. How much gravitational potential energy does it gain? Use Eₚ = m g h with g = 9.8 N/kg. → 39.2 JPrompt: Multiply mass, gravitational field strength and height.

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Conservation of energy and wasted energy.
  • Use concrete materials: wind-up toys or a pendulum.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Move on to: Work done, power and energy costs; Energy stored in a stretched spring (E = ½ k e²); Use energy conservation to find speeds and heights.
  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.

Free lesson plan from eurekami.com/lesson-plan-builder

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Kinetic and gravitational potential energy

Name

Date

Score/ 8

  1. Question 1

    A ball is dropped from 5 m. Ignoring air resistance, all its gravitational potential energy becomes kinetic energy. How fast is it moving just before it lands, in m/s? Use g = 10 N/kg.

    Answerm/s

  2. Question 2

    What is the kinetic energy of a 1000 kg object moving at 2 m/s? Use Eₖ = ½ m v².

    AnswerJ

  3. Question 3

    An object of mass 60 kg is lifted 2 m. How much gravitational potential energy does it gain? Use Eâ‚š = m g h with g = 9.8 N/kg.

    AnswerJ

  4. Question 4

    A ball is dropped from 10 m. Ignoring air resistance, all its gravitational potential energy becomes kinetic energy. How fast is it moving just before it lands, in m/s? Use g = 10 N/kg.

    Answerm/s

  5. Question 5

    What is the kinetic energy of a 60 kg object moving at 20 m/s? Use Eₖ = ½ m v².

    AnswerJ

  6. Question 6

    An object of mass 2 kg is lifted 20 m. How much gravitational potential energy does it gain? Use Eâ‚š = m g h with g = 9.8 N/kg.

    AnswerJ

  7. Question 7

    A ball is dropped from 20 m. Ignoring air resistance, all its gravitational potential energy becomes kinetic energy. How fast is it moving just before it lands, in m/s? Use g = 10 N/kg.

    Answerm/s

  8. Question 8

    What is the kinetic energy of a 80 kg object moving at 2 m/s? Use Eₖ = ½ m v².

    AnswerJ

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Answer key: Kinetic and gravitational potential energy

  1. 1. 10 m/s

  2. 2. 2000 J

  3. 3. 1176 J

  4. 4. 14.1 m/s

  5. 5. 12000 J

  6. 6. 392 J

  7. 7. 20 m/s

  8. 8. 160 J