Two-Wire Chronograph & Ballistic Velocity Lab MIT Experiment Physics

HIGH-SPEED OPTICAL RAIL & BREAK-WIRE SENSORS STATUS: READY TO FIRE
SCRUB: 0.00 ms
OSCILLOSCOPE PULSE DIAGRAM 200 µs/div
WIRE A BREAK (t₁) 0 µs
WIRE B BREAK (t₂) 2500 µs
TIME INTERVAL (Δt = t₂ - t₁)
2500.0 µs (0.002500 s)

Calibrated optical rail distance between Circuit Wire A and Wire B.

Projectile mass influencing kinetic energy and pendulum impulse transfer.

Muzzle energy velocity multiplier. Standard 80% charge targets 300 m/s.

Aerodynamic ballistic drag model causing deceleration across flight path.

Muzzle / Average Velocity (v = Δd / Δt)
300.0 m/s

Calculated via break-wire time interval Δt.

Flight Aerodynamic Drag Loss
1.8 %

Velocity drop over Δd due to air resistance.

Ballistic Pendulum Deflection
14.2 deg

Conservation of momentum impact deflection (M_pendulum = 1.5 kg).

EXPERIMENTAL TRIAL TELEMETRY LOG

MIT Bullet Speed Formula: v = Δd / Δt
Trial # Mass (g) Distance (m) Δt (µs) Velocity (m/s) Drag Loss (%) Pendulum θ (°)

PHYSICS PRINCIPLE: MIT TWO-WIRE CHRONOGRAPH

In classic MIT physics demonstrations, bullet velocity is measured without electronic radar by passing a projectile through two fine copper wire loops separated by a precise distance $\Delta d$. Breaking Wire A breaks an electrical circuit to start an microsecond timer counter. Breaking Wire B breaks a second circuit to stop the timer ($\Delta t$). The average flight velocity between the sensors is determined directly by $v = \frac{\Delta d}{\Delta t}$.