Runway and Braking

Runway and Braking is a free interactive simulation for GCSE Physics (Edexcel IGCSE 4PH1, spec point 1.10). Students practise v² = u² + 2as with any one of the four quantities as the unknown, and their answer is tested on a runway or a braking car. No login required.

v2 = u2 + 2as

v final speed u initial speed a acceleration s distance

Level

Question 1.1

Calculate the unknown on paper, type it into the highlighted row of the Results table, then press Run.

Instructions

  1. Choose a level, then click a row in the Results table to load that question.
  2. Read the question and write out your working on paper.
  3. Type your answer into the empty cell of that row. Use the units shown in the column heading.
  4. Press Run (or Enter). The vehicle moves using your value. Watch what happens at the marker and compare the speedometer needle with the gold pointer.
  5. When the run ends, the row is marked and a hint appears under the Run button. If you are correct, the next question loads automatically. If not, you can try again as many times as you like.

Results

Drag a term across the equals sign to move it to the other side. Drag a whole term by its + or − sign, or drag a single number or letter to divide by it. You can also tap a term, then tap the other side.

Make the subject:

Aim: To investigate whether the same equation can be used to find any one of v, u, a or s when the other three are known.

Part A — First observations

  1. Complete Level 1. Does the plane's final speed depend on its starting speed, or only on the runway and acceleration?
  2. For question 1.1, a student gives 1600 m/s as the answer. Does this look reasonable for a plane? Which step did they miss?

Part B — Finding the pattern

  1. Complete Levels 2 and 3. For each question, write down every step of your working. What is the first thing you did to both sides each time?
  2. Open Rearrange the equation and make s the subject. Which term did you move first, and why?
  3. Complete questions 5.1, 5.2 and 5.3. What happens to the braking distance each time the speed doubles?

Part C — Explaining formally

  1. Explain why u2 must be moved to the other side before you divide by 2a.
  2. In Level 5 the acceleration is negative. Explain what this means for the car, and what it does to the sign of the 2as term.
  3. A car travels at 15 m/s and can brake at 5 m/s². Then it travels at 30 m/s with the same brakes. Compare the two braking distances and explain the result in terms of the equation.

Part D — Applying the rule

  1. A student calculates a runway length and gets a negative answer. Suggest two different mistakes that could cause this.
  2. Write your own question where u is the unknown. Swap with a partner and check each other's working line by line.