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How does chemical energy in gasoline become motion in a car?
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mechanics
Figure 1: (A) The vector sum C = A + B = B + A. (B) The vector difference A + (−B) = A − B = D. (C, left) A cos θ is the component of A along B and (right) B cos θ is the component of B along A. (D, left) The right-hand rule used to find the direction of E = A × B and (right) the right-hand rule used to find the direction of −E = B × A.
In a gasoline-powered car, chemical energy is converted into mechanical motion through a process of controlled combustion within an internal-combustion engine. This process typically follows a four-stroke cycle:
- Intake: A mixture of gasoline vapor and air is drawn into the cylinder as the piston descends.1
- Compression: The piston ascends, compressing the mixture.1
- Power: An electric spark ignites the mixture. The resulting rapid expansion of hot gases creates high pressure that pushes against the piston head, performing work.213
- Exhaust: The piston ascends again to force the spent combustion products out of the cylinder.1
The linear, back-and-forth motion of the piston is converted into rotary motion by a slider-crank mechanism. This system uses a connecting rod to link the piston to a crankshaft; as the piston is driven by the combustion pressure, it forces the crankshaft to rotate, ultimately providing the power to move the vehicle.4