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The Physics of Classic Pullback Cars

In 1978, a Japanese company called Takara made the most famous pullback car in the world. The Choro-Q, referred to as “Penny Racers” in the United States, consisted of squeezed images of a real car. It also had a coil-spring pullback motor. These cars quickly became collectibles due to their low price and availability of special edition models. The pullback car has a metal or plastic outer shell, which houses a chassis with the gear box, axles, and wheels. The axle and back wheels are attached to the gear box, which contains gears. When the user turns the wheels, the axle winds the gears in the gear box, making the car move.

Physics Background

It is important to understand the difference between velocity and acceleration, especially when working with pullback cars. An object accelerates when its velocity changes, but velocity is not just a measure of speed. It also takes direction into account. Acceleration is when an object’s direction of motion, speed, or both change. An object can accelerate if it is moving in a straight line with changing speed or if it is moving in a circle with variable or constant speed.

If you close your eyes while moving at a constant velocity, you cannot even tell that you are in motion. This is why amusement ride designers would never create rides that move with constant velocity. You can feel the acceleration of amusement rides, especially rides like roller coasters and swings. For those who love these rides, the faster speed and direction change, the better. Acceleration occurs due to the action of an unbalanced force on an object. This falls under Newton’s Second Law of Motion, which states that acceleration is in direct proportion to the unbalanced force. The acceleration is inversely proportional to the object’s mass. This makes sense when thinking about the mass of cars and the power of their engines. Two cars with the same mass will not accelerate the same if they have different engines. Tractor trailers take much longer to get up to the speed limit due to their sheer size.

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Matt is the Managing Partner at Leland-West Insurance Brokers, Inc. He started with the firm while still a college student, way back in 1984. According to Matt his only remaining hobby is Motorsport ... because its all he can afford ("will work for tires"). Reach him at matt@lelandwest.com