How to play Stuck Bolt
- Choose a bolt and read the torque it needs, the grip distance r, the push F, and the angle φ on the card.
- Work out the lever arm, d = r·sin φ: the perpendicular distance from the bolt to the line of the push.
- Type the force, distance, or angle that gives just enough torque, τ = F·d, and press Push.
- Watch the gauge: the bolt breaks loose the moment the torque reaches the line. If the bar stops short, it stays stuck.
What makes a wrench turn a bolt?
A force turns an object about an axis with a turning effect called torque, or moment. It depends on how hard you push, how far from the axis, and in which direction. Only the part of the push perpendicular to the handle turns it, so τ = F·r·sin φ. The same torque is the force times the lever arm, τ = F·d, where d = r·sin φ is the perpendicular distance from the axis to the line of the push. A push straight along the handle has d = 0 and turns nothing. That is why you push a wrench at its end and at right angles to it, why a longer handle frees a stuck bolt, and why two hands on a cross wrench share the work.
A focused learning model
The wrench is rigid and each push is a single force at the hand. The bolt needs a fixed torque to break loose. The push grows steadily from zero over 2 s, and the bolt breaks loose exactly when the torque reaches that need, found exactly; a torque within 0.05% of it counts. A loose bolt then turns a quarter turn in 1 s while the push is held; a stuck bolt is watched for 1 s more. Torques are counter-clockwise positive, seen from above. Plays in real time.