Transportation questions

79 fact-checked questions — tap any to predict the answer, then read why.

• Why is it misleading to say that single-track vehicles like motorcycles mainly lean and stay stable because their wheels act like gyroscopes?
• Why does the front wheel of a leaned motorcycle often seem to find a useful steering angle without the rider holding it rigidly?
• Why can a tilted motorcycle tire help push the bike sideways through a curve instead of just rolling straight ahead?
• Why does taking the same motorcycle curve faster require noticeably more lean?
• Why does the bike-rider system need a lean angle when a motorcycle follows a steady road-speed curve?
• What actually happens just after a rider pushes the left grip forward to begin leaning a motorcycle left?
• Why can a motorcycle in a parking lot often steer around a cone with the front wheel pointed into the turn, even though road-speed turns use countersteering?
• Why can a motorcycle rider at normal riding speed start a right turn by briefly pushing the right grip forward instead of steering it like a car?
• After an airliner touches down, why do wing spoilers help the wheel brakes slow it down?
• Why can a plane lift off into ground effect near the runway but still need to accelerate before climbing away?
• Why is a landing approach speed kept above stall speed instead of being set as slow as the airplane can possibly fly?
• Why might pilots continue a takeoff after an engine failure past V1, the reject-or-continue decision speed, instead of braking immediately?
• Why does the same model of airliner usually need a faster landing approach when it is heavier?
• Why can an airplane stall in a steep level turn even if its speed seems safely above the usual straight-flight stall speed?
• Why do extended landing flaps let a plane fly slower without falling, even though they also create extra drag?
• Because lift depends on speed squared, if a plane slows from 100 knots to 90 knots with the same wing shape, angle of attack, and air density, what happens to its lift?
• Why does an airliner use high thrust on the takeoff roll even though it will later land at a much slower speed?
• Why is maximum GM not automatically the best target for a passenger ship?
• What design feature lets a steel cruise ship have lower average density than water?
• Icon of the Seas is listed near 250,000 GT. What is GT actually measuring?
• What are active fin stabilizers mainly designed to reduce while a cruise ship is moving?
• Why can a slack ballast tank weaken stability when the same tank pressed full would not?
• Same mass of ballast can sit high or low. Why do low tanks improve cruise-ship stability?
• For similar displaced volume, why does extra beam sharply improve a cruise ship’s roll stability?
• When a cruise ship heels a few degrees, what creates the first righting moment?
• Why can one runway crash cripple a whole airport?
• Why isn't a go-around always possible at the last moment?
• Why doesn't a radioed 'Stop!' mean instant braking?
• Why can one runway emergency make a second mistake more likely?
• Why do runway crashes often come from several small failures at once?
• Why doesn't a jet's anti-collision system simply stop a runway crash?
• Why can't a landing plane just swerve around a runway vehicle?
• Why can a last-second 'Stop!' call still fail on a runway?
• Why can a rescue truck itself become a runway hazard?
• Why can fewer nighttime flights still leave a runway vulnerable?
• Why do airports add surface radar instead of relying only on tower eyes?
• Why must airport fire trucks be electronically trackable on runways?
• Why do some buses tilt down at the front when stopped?
• Why do race cars have huge rear wings?
• Why do trains whistle at crossings?
• Why do elevators have weight limits?
• Why do ships use port and starboard?
• Why do traffic lights use red for stop?
• Why do ships have anchors?
• Why do planes dim cabin lights before night landing?
• Why do car engines idle?
• Why do school buses stop at railroads?
• Why do rockets need multiple stages?
• Why do tires have tread patterns?
• Why do bicycles need two wheels?
• Why do cars need transmissions?
• Why do helicopters hover without wings?
• Why do airplanes need runways?
• Why do ships have propellers at the back?
• Why do submarines dive and surface?
• Why are subway systems built underground?
• Why do high-speed trains have pointed noses?
• Why do ships have bulbous bows?
• Why do cars have alternators?
• Why are airplane windows rounded?
• Why don't cruise ships tip over?
• Why do motorcycles lean when turning?
• Why are roundabouts safer than intersections?
• Why do electric cars accelerate faster?
• Why do boats create waves behind them?
• Why do airplanes have winglets?
• Why are traffic lights red, yellow, green?
• Why do trains use steel wheels on tracks?
• Why do cars need oil changes?
• Why are ship anchors so heavy?
• Why do airplanes leave white trails in the sky?
• Why do hot air balloons float?
• Why do rockets need so much fuel?
• Why do helicopters have top rotors?
• Why do submarines sink and rise?
• Why do car tires have grooves?
• Why do bicycles stay upright moving?
• Why do ships have pointed fronts?
• Why do trains run on tracks?