How to calculate rolling friction?

Rolling friction is actually static friction. Only the zero boundary point of rolling friction and sliding friction can be calculated
If you insist on a number, it is equal to the static friction force (imagine the wheel at the contact point between the wheel and the ground. If the wheel takes the ground as the reference object, the wheel is stationary)

What does rolling friction have to do with it?
The friction between the bicycle wheel and the ground is rolling friction. When the bicycle tire is flat, it is more difficult to ride. Is it possible to say that the rolling friction is related to the contact surface area?

f=uN
Sliding friction and, friction coefficient (and contact of the two materials and roughness of the relationship) and positive pressure relationship!
Is the friction between the bicycle wheel and the ground rolling?
Static friction: Although the wheel rolls, there is no relative sliding when the wheel contacts the ground
When a bicycle tire is flat, it's hard to ride. Can we say that the rolling friction is related to the contact surface area?
The size of sliding friction has nothing to do with the contact area, but the reason for the effort is the change of its torque

Thermal power plant is the use of coal chemical energy into electricity and power generation

Chemical energy thermal energy mechanical energy electrical energy

What are the dimensions of the earth?

How many grams is six ounces?

1 oz = 0.028349523125kg = 28.349523125g
Multiply by 6 and it's 170.09713875 grams

Factorization: A & # 178; - B & # 178; + 6b-9

a²-b²+6b-9
=a²-(b-3)²
=(a+b-3)(a-b+3)

How to calculate current when superconductor resistance is zero?
If the resistance of superconductor is zero, is ohmic circuit not applicable?
Also, how to calculate the current of superconductor without ammeter?

In practical application, the current of superconducting object is mainly determined by the input current of peripheral circuit. For itself, unless the whole circuit including power supply is made of superconductor, the current flowing through it is infinite in ideal case

When an object starts to make a uniformly accelerated linear motion with the acceleration of A1 from the static point a, it reaches point B after time T. at this time, the acceleration of the object becomes A2, and the direction is opposite to that of A1. After time t, the object returns to point a, then the ratio of A1 to A2 is ()
A. 1﹕3B. 1：1C. 1﹕2D. 1﹕4

The velocity direction of uniform acceleration is positive ① x1=12a1t2… ② For the uniform deceleration process (returnable), there are: & nbsp; x2 = vbt-12a2t2 ③ The questions are: X1 = - x2 ④ A: A: a 2 = 1:3, so a: a 2 = 1:3

Please write the mathematical expression of the expansion coefficient β with the symbols of physical quantities learned in junior high school physics
The heat absorbed (released) by a material of potential mass at 1 ℃ is called the specific heat capacity of the material. Its mathematical expression is expressed as C = q / m △ t (where △ T represents the change of temperature). Different materials have different specific heat capacities. Similarly, different materials have different thermal expansion ranges, which can be expressed by volume expansion coefficient β, The volume change when the temperature increases by 1 ℃ is called the volume expansion coefficient of this substance. The following is the volume expansion coefficient of some solids and liquids when the pressure is constant and close to room temperature

By definition:
Unit... Radiomolecule,
Every. Radiomolecule
In addition, put the denominator position

The board with length of L and mass of M is still on the smooth horizontal table. A small block B with mass of m just falls on the left end of board a with horizontal velocity v0. The friction coefficient between board B and board a is u, and block B can be regarded as a particle. How large is V0 if B just reaches the right end of board a

First, momentum is conserved
When the system is stable, the common velocity of M and M is v,
m*V0=(m+M)*V
Kinetic energy conservation:
1/2*m*V0^2=1/2*(m+M)*V^2+f*L
f=u*m*g
Then we can get v0

How to calculate rolling friction?