Mass is a fundamental property of objects. It does not change with changes in the shape, state and position of the object

Represented by the letter m

Definition: How much matter an object contains

Quality measurement: Commonly used tools for measuring quality include steelyard scales, case scales, bench scales, electronic scales, balances, etc. Laboratory balance with pallet to measure mass

Conversion

Definition of density: The mass of a certain substance per unit volume is called the density of the substance

Definition formula: P=m/v (not a determinant, density is a characteristic of matter)

Density measurement: Use a balance to measure the mass of a liquid, and use a graduated cylinder to measure the volume of the liquid. Find density using density formula

Equipment: stones, beakers, balances and weights, enough water, thin wire (1) Use the adjusted balance to measure the mass of the solid to be measured (2) Fill the beaker with water, use the balance to measure the beaker and water (3) Use a thin wire to pull the stone and immerse it in the beaker. After the liquid overflows, use a balance to measure the total mass of the beaker at this time.

Equipment: Beaker, enough water, enough liquid to be measured, balance and weights: (1) Use the adjusted balance to measure the mass of the empty beaker (2) Fill the beaker with water, use the balance to measure the mass of the beaker and The mass of water is (3) Empty the water in the beaker, and then fill the beaker with the liquid to be measured. The mass of the beaker and liquid is measured at this time.

Equipment: measuring cylinder, solid to be measured, water, thin wire (1) Put appropriate amount of water into the measuring cylinder and read the time (2) Put the solid to be measured into the water in the measuring cylinder and read the time (3) Use a pin to press the object completely into the water and read the reading.

Common forces: gravity, friction, elasticity, buoyancy

force effect

Represented by the letter N

How force is measured: spring dynamometer

Three elements of force: magnitude, direction, and point of action

Force analysis diagram

inertia

Two force balance

Definition: The pressure exerted on an object per unit area is called pressure

Physical meaning: Pressure is a physical quantity that expresses the effect of pressure

Formula: p=F/s

Methods to increase or decrease pressure: change the size of the pressure, change the size of the stressed area

liquid pressure

Atmospheric pressure: Torricelli experiment

The relationship between gas pressure and flow rate: In gases and liquids, the greater the flow rate, the smaller the pressure.

Archimedes' Principle: The buoyant force on an object immersed in a liquid is equal to the gravitational force on the liquid it displaces.

Formula: F float = G row = ρ liquid V row g

Applications of buoyancy: ships, submarines

Object sinking and floating conditions

work and power

Mechanical energy