Mass, Weight and Density Flashcards
Aligned with Kognity
Define Weight
A gravatational force on an object that has mass, measured in newtons.
Define Mass!
A measure of the quantity of matter in an object at rest
Rocks in an area with no gravity, still have the same mass.
What is the gravitational field strength?
The force of gravity on an object per unit mass (N/kg).
It tells us the weight experienced by a mass in that place.
Every 1kg of mass is pulled downwards with a force of…
9.8 newtons.
(on earth)
How do you calculate the gravitational field strength?
g = W/m (measured in N/kg) (Paste image of triangle)
weight is measured in N, Mass in kg, grav field strength in N/kg
How do you calculate gradient m?
m = (change in y)/(change in x)
Delta symbol (triangle) = change
How do you calculate g,w or m on a graph?
w is the y axis, m is the x axis and g is the gradient (rise/run).
Describe gravitational field strength in relation to an object in free fall.
The gravitational field strength is equivalent to the acceleration of free fall of an object in that gravitational field.
What is density?
Density is commonly expressed in units of grams per cubic centimeter (g/cm³) and measures how compact or tightly packed matter is within a given space.
What is the density of water?
1.0 g/cm^3 = 1000 kg/m^3
What is the density formula?
p (kg/m^3) = m (kg)/v (m^3)
p = density
What is the typical density (g/cm^3) of air and gold?
air = 0.001 g/cm^3
gold = 19.0 g/cm^3
What’s the equation used to calculate the volume of a sphere?
V = 4/3 pi r^3
What is a parallax error?
When you take a reading from a ruler or other equipment and your eyes aren’t level with the scale.
What’s a good way to increase accuracy when measuring density?
Conduct the experiment numerous times, then calculate and average.
How would you measure the density of an inregular pebble?
Use the displacement of water to measure the density of irregular objects, provided the object dosen’t dissolve or react with water. If it does, use another liquid like vegetable oil.
Vpebble = Vpebble + water - Vwater
What’s a cubic decimeter (dm^3)?
A litre
1 cm^3 of water has what mass in grams?
1 g
1000 cm^3 of water (= 1dm^3 = 1L = 1000ml) has a mass of…
1kg = 1000g
1m^3 of water = 1000dm^3 has a mass of…
1000kg = 1 tonne
Why will an object float?
An object will float if its average density is lower than that of the liquid.
When designing a boat, what does the average density need to be? And how is this achieved?
The average density needs to be below 1 g/cm^3. This is achieved by having enough air inside the boat.
