definition

Diffusion speed

Nature

The phenomenon of diffusion explains

Gravity Example: Tension spring - produces gravitational force

Repulsive force Example: Compression spring - generates repulsive force

The simultaneous attraction and repulsion between molecules are collectively called forces

Objects are composed of a large number of molecules. The molecules are constantly moving irregularly. There are attraction and repulsion forces between the molecules.

The sum of the kinetic energy of all molecules of an object and the potential energy of intermolecular interactions

! ! ! Special note: The molecules of all objects are constantly moving irregularly, so all objects have internal energy [Note: it is all objects] and the internal energy cannot be 0

The direct transfer of internal energy from one object to another

Convert other forms of energy into internal energy or internal energy into other forms of energy

1. For the same substance, the internal energy will definitely increase as the temperature increases, but the temperature does not necessarily increase as the internal energy increases. Example: Ice melts into water.

2. When work is done on an object, the internal energy increases and the temperature rises. The temperature of an object that performs work on the outside decreases

Definition: We call the ratio of the heat Q released by complete combustion of the fuel to the fuel mass m, called the calorific value of this fuel. The symbol is represented by q.

q=Q/m

The calorific value of fuel is only related to the type of fuel (the calorific value of different fuels is generally different)

Method: Control variable method

The mass is equal, the temperature is the same, the heating time is the same

Conclusion: The amount of heat an object absorbs is not only related to its mass and temperature changes, but also related to the substance it is.

The unit of c is: J/(kg.℃)

The unit of Q is: J

The unit of m is: kg

The unit of Δt is: ℃

1. Specific heat capacity is a characteristic of a substance and is only related to the type and state of the substance.

2. Different substances generally have different specific heat capacities.

3. The specific heat capacity of liquids is generally greater than that of solids