Free fall and fall with air resistance
PhysicsKinematicsAges 15–16Virtual lab
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Kinematics
Two objects of different mass and cross-section are dropped together from the same height. With drag off, both hit the ground at the same time, v = gt. With drag on, the lighter object with more drag reaches terminal velocity and falls more slowly. The v(t) graph and distance fallen update in real time. A Lab screen measures g with an electromagnet and light gates (the gradient of 2h against t² is g) and fits coffee-filter v(t) data with linear (bv) and quadratic (cv²) drag models.
Lesson: Free fall
What it shows
Without air, every object falls with the same acceleration g whatever its mass, so v = gt and the fall time t = √(2h/g) is the same for a heavy and a light object. In air, drag opposes the motion; the lighter sphere has a larger area-to-mass ratio, so it reaches a lower terminal velocity and lands later. The Lab screen turns this into practicals: timing a steel ball from an electromagnet to a light gate at several heights gives g as the gradient of 2h against t², and dropping nested coffee filters shows whether F = bv or F = cv² fits the data.
How to use
Turn Enable air resistance off, press Drop again and compare the landing times and v(t) lines of Object 1 and Object 2; then turn it on and repeat. On the Lab screen, choose g with light gates, set Drop height h, press Switch off magnet three times at each height and read g from the graph. Or choose Drag on coffee filters, drop 1 to 8 filters, Record each terminal velocity and compare the graphs against m.
Parameters you can change
- Drop height 5–120 m
- Acceleration due to gravity 1.6–11 m/s²
- Mass of object 1 0.05–10 kg
- Mass of object 2 0.05–10 kg
- Enable air resistance
- Screen Drop two objects, Lab
- Experiment (Lab screen) Measuring g with light gates, Drag on coffee filters
- Light-gate drop height h (Lab) 0.1–1.5 m
- Number of nested coffee filters n (Lab) 1–8
Questions to explore
- Why do a feather and a steel ball fall at the same rate in a vacuum?
- When an object reaches terminal velocity, how does the drag force compare with its weight?
- If the drop height is made four times larger without air resistance, how many times longer does the fall take?
Teaching ideas
All guides- How to Remix a Simulation for Your Class with AIRemix a simulation from the library with AI for 20 credits: change the context, units or graphs, keep the working model, check it and share it with your class.
- Using Simulations for HomeworkUsing simulations for homework: design tasks students can do on a phone, check answers automatically, set deadlines, and use 3 ready tasks with answers.
- Predict–Observe–Explain with SimulationsPredict–observe–explain with simulations: lock in predictions, run the experiment, discuss the gap. A full worked example, prompts and discussion moves.
- Reaction Time Virtual Lab: The Ruler Drop TestReaction time virtual lab: time your own ruler catches, convert drop distance to time, then use a simulated class to test distraction, sound and caffeine.
