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Science lesson plan · 10th grade (Year 11 in England) · 30 minutes

Use energy conservation to find speeds and heights

Energy

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

Objective and success criteria

Students will: Use energy conservation to find speeds and heights.

  • 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: Kinetic and gravitational potential energy; Conservation of energy and wasted energy

Leads to: the next skill in this area.

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 · 4 min

  • Quick retrieval from earlier learning (Kinetic and gravitational potential energy; Conservation of energy and wasted energy). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  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. A lamp is supplied with 100 J of energy. It transfers 60 J usefully. How much energy is wasted, in J? → 40 JPrompt: Energy is conserved: input = useful output + wasted output.
  3. An object of mass 10 kg is lifted 3 m. How much gravitational potential energy does it gain? Use Eₚ = m g h with g = 9.8 N/kg. → 294 JPrompt: Multiply mass, gravitational field strength and height.

Hook · 3 min

  • Wind up a toy or stretch an elastic band and ask where the energy goes.
  • Share the objective: Use energy conservation to find speeds and heights. Read the success criteria together.

I do: model it · 7 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: A ball is dropped from a height of 5 m. Ignoring air resistance, how fast is it moving just before it hits the ground, in m/s? (g = 9.8 N/kg; give 1 decimal place)
  • Step 1: v = √(2 × 9.8 × 5) = √98 = 9.9
  • Step 2: So the answer is: 9.9 m/s
  • Answer: 9.9 m/s
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 6 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. A ball is dropped from a height of 80 m. Ignoring air resistance, how fast is it moving just before it hits the ground, in m/s? (g = 9.8 N/kg; give 1 decimal place) → 39.6 m/sPrompt: GPE lost = KE gained: m g h = ½ m v²
  2. A skateboarder leaves the bottom of a ramp at 14 m/s. Ignoring friction, what is the greatest height they can reach, in m? (g = 9.8 N/kg; give 2 decimal places) → 10 mPrompt: All the kinetic energy becomes gravitational potential energy.

You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A 10 kg object falls 2 m. 10 % of its gravitational potential energy is transferred to the surroundings by air resistance. How much kinetic energy does it have at the bottom, in J? (g = 9.8 N/kg; give 1 decimal place) → 176.4 JPrompt: First find the GPE lost: m g h.
  2. A ball is dropped from a height of 2 m. Ignoring air resistance, how fast is it moving just before it hits the ground, in m/s? (g = 9.8 N/kg; give 1 decimal place) → 6.3 m/sPrompt: GPE lost = KE gained: m g h = ½ m v²

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: Kinetic and gravitational potential 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

  • 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-10.

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

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Use energy conservation to find speeds and heights

Name

Date

Score/ 6

  1. Question 1

    A ball is dropped from a height of 10 m. Ignoring air resistance, how fast is it moving just before it hits the ground, in m/s? (g = 9.8 N/kg; give 1 decimal place)

    Answerm/s

  2. Question 2

    A 0.5 kg object falls 10 m. 25 % of its gravitational potential energy is transferred to the surroundings by air resistance. How much kinetic energy does it have at the bottom, in J? (g = 9.8 N/kg; give 1 decimal place)

    AnswerJ

  3. Question 3

    A skateboarder leaves the bottom of a ramp at 7 m/s. Ignoring friction, what is the greatest height they can reach, in m? (g = 9.8 N/kg; give 2 decimal places)

    Answerm

  4. Question 4

    A ball is dropped from a height of 2 m. Ignoring air resistance, how fast is it moving just before it hits the ground, in m/s? (g = 9.8 N/kg; give 1 decimal place)

    Answerm/s

  5. Question 5

    A 5 kg object falls 5 m. 40 % of its gravitational potential energy is transferred to the surroundings by air resistance. How much kinetic energy does it have at the bottom, in J? (g = 9.8 N/kg; give 1 decimal place)

    AnswerJ

  6. Question 6

    A skateboarder leaves the bottom of a ramp at 20 m/s. Ignoring friction, what is the greatest height they can reach, in m? (g = 9.8 N/kg; give 2 decimal places)

    Answerm

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Answer key: Use energy conservation to find speeds and heights

  1. 1. 14 m/s

  2. 2. 36.8 J

  3. 3. 2.5 m

  4. 4. 6.3 m/s

  5. 5. 147 J

  6. 6. 20.41 m