mass, weight and density Flashcards
Mass is…
- The amount of matter the object contains.
- It’s measured in g/kg.
Weight depends on…
- The gravitational force acting on it. The greater the mass, the greater the force acting on it.
- It’s measured in Newtons (N)
What is the gravitational force on earth?
9.8N/kg
What happens to the mass and weight if we move an object away from the earths surface?
- The mass will stay the same
- The weight will change as gravity changes
If your mass was 75kg, what would your weight be?
750N (rounded 9.8 to 10)
The volume tells us…
- How much space an object takes up.
- It’s measured in cm3 or m3
The density of a material…
- Tells us the mass of km3/m3
- It’s measured in g/cm3 or kg/m3
What’s the formula for density?
- D = M/V
- ( Density = Mass over Volume )
What’s the formula for Mass?
- M = D x V
- ( Mass = Density x Volume )
What’s the formula for Volume?
- V = M/D
- ( Volume = Mass over Density )
How do we measure mass?
By placing the object on digital scales
How do we measure volume? ( regular )
- We measure the length, breath and height.
- then calculate it by multiplying l x b x h.
How do we measure volume? ( irregular )
- we fill the measuring cylinder with a known amount of water and take note of the volume.
- We lower the object into a measuring cylinder.
- the change in volume shown, is the volume of the object
How do we measure volume? ( irregular and floats )
- fill the measuring cylinder to a known amount of water.
- tie a weight onto it and lower it into the measuring cylinder.
- however much the water rises, will be the volume of the object plus weight, so find the volume of weight and subtract it.
If the mass of an object is 440g and the volume was 40cm3, what is the density?
D = M/V
= 440/40
= 11g/cm3
