Physic Labs

Newtonian mechanics

Newton's three laws, energy, and collisions

Directly observe Newton's second law (ΣF = ma), the work-energy theorem, and conservation of momentum in collisions, by changing parameters yourself and watching how the system responds. Measure net force and acceleration, and compare energy and momentum readings with their conservation relations ΣF=maΣF = ma.

Middle school

Equipment

  • Virtual inclined plane with adjustable angle and friction coefficient
  • Curved track (parabolic or with a hill), frictionless or with friction
  • Two colliding spheres, coefficient of restitution e adjustable from 0 to 1

Procedure

  1. Test Newton's first and second laws

    In section 1, set the pulling force F = 0 and slowly increase the incline angle θ until the object starts to slide. Compare with the theoretical threshold tanθ = μ. Then turn on the pulling force F and watch the acceleration a = ΣF/m change instantly as you drag the slider. Compare the displayed values with ΣF=maΣF = ma.

  2. Verify conservation of mechanical energy

    In section 2, set friction μ = 0 and release the ball. Watch the stacked chart: the total height of U + K must always equal the initial energy. Then increase μ > 0 and watch the Q (heat) band appear, eating into U + K. Compare the displayed values with U+K=constantU + K = constant.

  3. Compare elastic and inelastic collisions

    In section 3, run the collision with e = 1, then with e = 0, keeping the same masses and initial velocities. Read the momentum/energy panel: momentum is always conserved, but kinetic energy is conserved only when e = 1. Compare the displayed values with pbefore=pafterp_{before} = p_{after}.

Simulation

Experiment history

Isaac Newton published his laws of motion in the Principia in 1687, providing a unified account of forces and motion on Earth and in the heavens. The second law, ΣF = ma, relates acceleration to net force and mass; together with the third law for interacting bodies, it explains motion on an incline and velocity changes in collisions. These laws became a foundation of classical mechanics, although a real analysis must define the system and identify external forces. The work–kinetic-energy theorem relates net work to the change in kinetic energy, W_net = ΔK. In an isolated collision, total momentum p = mv is conserved, while kinetic energy is conserved only for an elastic collision. The simulations distinguish these conservation laws. Vary mass, force, friction, or restitution and compare the motion with the displayed quantities; the numerical models omit details such as material deformation and losses outside their assumptions.

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