Bicycle physics, knowledge of physics in bicycles

When a person pushes a bicycle, the friction of the front and rear wheels is backward, and when a person is riding a bicycle, the friction of the front wheel is backward, and the friction of the rear wheel is forward. Explanation: First of all, it is necessary to understand the definition of friction. (So detailed, give some face, I'll do it!)

The first thing that is clear is the friction experienced by the moving bike.

For the moving bicycle, for the front wheel, because the driven wheel, its motion is passive, so the friction force is resistance to the movement of the front wheel, because the bicycle is moving forward, so the direction of friction on the front wheel is opposite to the direction of movement.

For the rear wheel, the same direction of motion is forward, but different from the front wheel, the part of the rear wheel as the power output is the driving wheel, and the direction of the forward rotation force of the rear wheel on the ground is backward, and the friction force as a reaction force must be equal to the direction of the rotation force, so the direction of the friction force received by the rear wheel should be forward.

If the feeling of the rear wheel is not easy to understand, you can also feel it like this, for example, on an extremely smooth ground, the bicycle cannot be driven, because there is no friction, that is to say, there is no friction to push the reaction force, so it cannot be driven, so it is better to understand.

I hope mine is helpful or enlightening to you and have a great time.

The physics knowledge in the bicycle is as follows:

Why do bicycle tires have uneven patterns?

The amount of friction is related to two factors: the amount of pressure and the roughness of the contact surface. The greater the pressure, the greater the friction; The rougher the contact surface, the greater the friction.

The outer tire of the bicycle has a convex and uneven pattern, which increases the friction by increasing the roughness between the bicycle and the ground, and its purpose is to prevent the bicycle from skidding.

Why do bicycles move forward?

When we ride on a bicycle, there is friction between the bicycle and the road surface because the person and the bicycle have pressure on the ground, and the tire and the ground are not smooth, but why does the bicycle move forward? Again, this is caused by the friction between the rear wheels and the ground, and the direction of this friction is forward.

So what does the friction of the front wheel do? Hinder the movement of the car! It goes in the opposite direction to the direction in which the bicycle is traveling.

It is these two forces that are equal in magnitude and opposite in direction, so the bicycle moves at a uniform speed. However, when people push their bicycles on the ground, the friction of the front and rear wheels is backwards. So who is in balance with these two forces?

The friction of the foot against the ground forward!

Why does the bike stop after braking?

When braking, the friction between the brake pad and the rim hinders the rotation of the rear wheels. The greater the pressure on the hand, the greater the pressure on the rim and the greater the friction generated, the slower the rear wheels will rotate.

If the brakes are completely rough, the friction between the rear wheel and the ground becomes a sliding friction (originally a rolling friction, the direction is forward), and the direction is backward, hindering the movement of the bicycle, so it stops.

Where are steel balls installed on bicycles? Why Angangzhu?

Steel balls are installed on the front axle, middle axle, rear axle, handlebar rotation, pedal rotation and other places of the bicycle.

People always want to ride a bike with ease, flexibility, and effort. And using rolling instead of sliding can greatly reduce friction, so to install steel balls where the bike turns, we can often add lubricating oil to make the contact surfaces move away from each other, so that the friction can become smaller.

The physical knowledge of bicycles includes mechanical, thermal and optical knowledge such as levers, axles, friction, pressure, and energy conversion.

1. Knowledge of mechanics.

1. Friction:

1) Some patterns are engraved on the tires, handlebar covers, pedals and brake pads of the bicycle to increase the roughness of the contact surface and increase the friction.

2) Some lubricating oil is often applied to the axle to reduce the roughness of the contact surface and reduce the friction.

3) There are balls at all axles, which change the sliding friction to rolling friction to reduce the clan friction and make it easy to rotate.

4) when braking, need to tighten the brake handle, to increase the pressure between the brake block and the rim, thereby increasing the friction, 5) when the bicycle is pressed forward, the direction of friction that the rear wheel receives is forward, is the power of the bicycle forward, and the direction of the friction force received by the front wheel is backward, is the resistance of the bicycle forward;

When the bicycle moves forward by inertia, the friction force experienced by the front and rear wheels is in the direction of backwards, and both forces are the resistance of the bicycle to move forward.

2. Pressure signs:

1) In general, the landing area of a fully inflated bicycle tire is approximately.

s=2 10cm 5cm=100 cm2, when an ordinary adult rides a bicycle forward, the pressure of the bicycle on the ground is about f=(500N+150N)=650N, and the pressure of the bicycle on the ground can be calculated as.

2) A washer should be added to the nut of the axle to increase the stress area and reduce the pressure.

3) The pedal of the bicycle is made flat and flat, and the Tongsui is rented to increase the stress area to reduce its pressure on the foot, 4) The inner tube of the bicycle should be filled with enough gas, and when the volume and temperature of the gas are constant, the greater the mass of the gas, the greater the pressure.

5) The saddle of the bicycle is made flat and flat to increase the force area to reduce its pressure on the body.

3. Axles:

2) The pedal and bottom bracket of the bicycle are also equivalent to an axle, which is essentially a labor-saving lever.

3) The flywheel of the bicycle is also equivalent to a labor-saving axle.

It is said that no machine can save work, but its bicycle does save work compared to walking. Why is that? Because the bicycle changes the details of the movement, it saves the work caused by the change of the center of gravity of the body when walking, so the bicycle reduces the useless work and improves the efficiency.

This should be an enumeration question, right?

Just name one or two, because there's so much knowledge in it.

Among the 25 components of a bicycle, such as the frame, tires, pedals, brakes, and chains, the basic components are indispensable. Among them, the frame is the skeleton of the bicycle, and it carries the most weight of people and cargo. According to the working characteristics of each component, it can be roughly divided into guide system, drive system and braking system

1. Guidance system: composed of handlebar, front fork, front axle, front wheel and other components. The rider can change the direction of travel and maintain body balance by manipulating the handlebars.

2. Drive (transmission or walking) system: composed of pedals, bottom bracket, crankset, crank, chain, flywheel, rear axle, rear wheel and other components. The pedaling force of the human foot is transmitted by the pedal through the crank, sprocket, chain, flywheel, rear axle and other components, so that the bicycle continues to move forward.

3. Braking system: It is composed of brake components, and the rider can manipulate the brake at any time to slow down and stop the bicycle to ensure driving safety. In addition, for safety and aesthetics, as well as for practicality, it is also equipped with parts such as lights and brackets.