Collision Lab Simulator

Momentum is the one quantity a collision cannot destroy. In this collision lab you set both carts' masses and velocities, choose elastic (bouncy, kinetic energy kept) or perfectly inelastic (sticky, kinetic energy lost to deformation and heat), then watch momentum balance exactly while energy tells a different story in each mode.

Controls

• Mass 1: Mass of the left cart in kg.
• Mass 2: Mass of the right cart in kg.
• Velocity 1: Initial velocity of the left cart in m/s. Positive moves right.
• Velocity 2: Initial velocity of the right cart in m/s. Negative moves left.
• Elastic / Inelastic: Elastic: carts bounce apart, kinetic energy conserved. Inelastic: carts stick together, maximum kinetic energy lost.

The physics

Assumptions

• Head-on collision in one dimension
• No external impulse acts during the brief impact
• No friction or air drag during the collision itself
• Carts are point masses for the velocity calculation

Guided activity

1. Set equal masses (1 kg each), v_1 = 2 m/s, v_2 = 0, elastic mode. Watch the carts trade velocities — the moving one stops dead. This is the Newton's cradle effect.

2. Keep it elastic but make m_1 = 3 kg and m_2 = 1 kg. Which cart leaves faster? Check momentum before and after.

3. Switch to perfectly inelastic (stick together) with equal masses and v_2 = 0. What fraction of the kinetic energy survives? Compute it from the velocities.

4. Set m_1 = m_2 = 1 kg, v_1 = 3 m/s, v_2 = -3 m/s, elastic. Predict the outcome from symmetry, then run it.

Challenge questions

1. In the equal-mass elastic case, prove from the two conservation equations that the carts must exchange velocities.

2. In a perfectly inelastic collision of equal masses (one initially at rest), exactly half the kinetic energy vanishes. Where does it go? List the physical channels.

3. A 3 kg cart at 2 m/s hits a stationary 1 kg cart elastically. Use the elastic formulas to find both final velocities, then verify momentum is conserved.