Newton's second law – pulling a block on a surface
PhysicsForces & DynamicsAges 15–16Virtual lab
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Forces & Dynamics
Pull a block of mass m with force F along a horizontal or inclined surface with friction μ. Watch the force vectors (F, W, N, f), the acceleration a = (F − f − W·sinα)/m, and a real-time velocity-time graph v(t). Drag the F slider right in the simulation, or drag the block to reposition it. Two more screens: a trolley pulled by hanging masses over a pulley and timed by two light gates (a against F at constant mass and against 1/m at constant force, with a–F and a–1/m graphs), and a spring-balance comparison of rolling and sliding friction.
Lesson: Newton's second law, friction, motion on an inclined plane
What it shows
Newton's second law states that acceleration equals the resultant force divided by mass, a = ΣF/m. On the first screen a block is pulled along a level or inclined surface: the pull F, the weight W, the normal reaction N and kinetic friction f = μN act on it, and the v(t) graph shows that force sets the acceleration, not the velocity. The trolley lab tests the law with hanging masses and two light gates: a ∝ F at constant mass, a ∝ 1/m at constant pull. The third screen pulls a block, a roller and a ball-bearing cart of equal weight with a spring balance: rolling friction is far smaller than sliding friction.
How to use
On Pulling a block, change F and the angle α and compare the slopes of v(t). On Trolley and pulley, tick Friction compensated (runway tilted), set the 20 g masses on the hanger and press Release; repeat with other masses, then add 250 g masses on the trolley and switch the graph to a – 1/m. On Rolling vs sliding, choose an Object and a Surface, press Pull slowly and read the Spring balance.
Parameters you can change
- Pulling force F (along the surface) 0–50 N
- Mass of block 0.5–10 kg
- Coefficient of friction μ 0–1
- Angle of incline α 0–45 degrees
- Screen Pulling a block, Trolley, pulley and light gates, Rolling and sliding friction
- Number of 20 g masses on the hanger 0–8
- Number of 250 g masses on the trolley 0–4
- Friction compensated (runway tilted)
- Object pulled Wooden block, Roller, Cart on ball bearings
- Surface Wooden board, Glass sheet, Cloth
- Extra 1 N weights 0–3
- Spring balance 0–5 N, 0–1 N
Questions to explore
- Why is the normal reaction N smaller than the weight W when the block is on an incline?
- What is the minimum pulling force needed to move the block up the slope at constant velocity?
- Without friction, if both m and F are doubled, how does the acceleration change?
Teaching ideas
All guides- Interactive Physics Lesson Ideas with SimulationsInteractive physics lesson ideas for grades 6–12: ten simulation activities in mechanics, waves, light, electricity, heat and modern physics, with real values.
- Forces and Motion Lesson Plan with SimulationsA forces and motion lesson plan with free simulations: net force, friction and F = ma, with predictions, expected readings and a five-question set.
- Impulse Virtual Lab: Force–Time Graphs and Crash SafetyAn impulse virtual lab: crash a cart into a force sensor with four bumpers, read peak force and contact time, and see why crumple zones and airbags work.
