chp4

1. mass

1.1. amount of matter in a body

1.2. kg

1.3. scalar

2. gravitational field strength

2.1. g

2.2. the gravitational force acting per unit mass

2.3. N/kg

2.4. on earth,g=10N/kg

3. weight

3.1. amount of gravitational force acting on an object

3.2. N

3.3. weight=mass *g

4. inertia

4.1. the inertia of an object refers to the reluctance of the object to change its state of rest or motion,due to its mass

4.2. mass↑，inertia↑

5. density

5.1. density is defines as a substances's mass per unit volume

5.2. density=mass/volume

5.3. SI unit：kg/m³

5.4. 1000kg/m³=1g/cm³

5.5. floating and sinking

5.5.1. density of an object>density of the liquid:sinking

5.5.2. density of an object<density of the liquid:floating

5.5.2.1. the denser the liquid,the higher an object will float in the liquid