(a) application of motion and force
Bicycle tires, plastic handlebars, pedal sleeves and brake handlebars all have uneven patterns to increase friction. When braking, you should hold the brake handle by hand to increase the pressure of the brake pad on the rim and stop the wheel from rolling. When braking, the wheels stop rolling and slide on the ground, and the friction is greatly increased, so the car can brake quickly.
Rolling bearings are used in front axle, intermediate axle and rear axle of automobiles to reduce friction. People often add lubricating oil to these parts to further reduce friction.
1. Increase and decrease friction
Knowledge of bicycle machinery
A thick coil spring is installed under the car seat cushion to reduce vibration.
2. Damping effect of spring
Knowledge of bicycle machinery
(B) the application of stress knowledge
Bicycle tires are engraved with load capacity, which clearly tells people not to overload. If the vehicle load is too large, the tire stress area will remain unchanged, and the tire will be crushed if it is stressed too much.
1. Bicycle load
2. Physics in car seats
The seat cushion is saddle-shaped, which can increase the contact area between the seat cushion and the human body, so as to reduce the pressure on the buttocks and make people feel more comfortable when riding.
Knowledge of bicycle machinery
(C) the application of simple mechanical knowledge
Brake handle and connecting rod in bicycle brake system are labor-saving levers, which can increase the tension of brake shoe. In addition, sprocket and pedal, rear wheel and flywheel, faucet and rotating shaft are all wheel shafts, which can save labor.
Knowledge of bicycle machinery
(d) Knowledge application of work and energy
1 When riding a bicycle on a steep slope, people often take the "S" route, which is based on the principle of work. As shown in the figure, the slope length is equivalent to the slope length and the slope height is equivalent to the slope height. According to the working principle, W 1=W2, that is, FL=Gh, can also be written as:, which shows that the slope length L is several times the slope height H.
Knowledge of bicycle machinery
(d) Knowledge application of work and energy
2. Mutual transformation between kinetic energy and potential energy
Before riding a bicycle uphill, people often have to step on the pedal several times to increase the speed (kinetic energy) of the car. "kinetic energy rushing uphill" converts greater kinetic energy into greater potential energy, so it is easier to reach the top of the slope. But when riding downhill, the speed is getting faster and faster, and you don't pedal. This is because the potential energy is converted into kinetic energy, and the kinetic energy is increasing, so the speed is also increasing.
Knowledge of bicycle machinery
(5) Braking and inertia
When a bicycle is driving at a high speed, especially when going downhill, it is not allowed to use the front brake alone, otherwise a rollover accident will occur. The reason is that the front wheel is forced to stand still when braking, and the rear wheel frame and cyclist as driving wheels have to keep the original trend of high-speed movement due to inertia, and then the contact between the front wheel and the ground will serve as a fulcrum, thus causing a rollover accident.
Knowledge of bicycle machinery
(6) Application in measurement
When measuring road length, you can use bicycles. For example, the diameter of type 24 wheel is 0.62m, the diameter of type 26 wheel is 0.66m, and the length of one circle of the wheel is the diameter multiplied by pi to get 1.95m or 2.07m Then, let the car roll along the runway and record the number of laps it has rolled, and the length of the runway is n× 1.95m or.
Knowledge of bicycle machinery
(7) Application of thermal expansion knowledge
In hot summer, don't inflate the air in the tire too much, and don't expose yourself to the scorching sun, because the air in the tire expands sharply when heated, and the tire will burst when the air pressure increases sharply.
Knowledge of bicycle machinery
(8) Transformation of mechanical energy and internal energy
Pump up the tire with a pump, and the cylinder wall will heat up after a while. This is because compressing the gas in the cylinder and overcoming the friction between the piston and the cylinder wall will increase the internal energy of the cylinder wall and raise the temperature, so the cylinder wall will heat up.