Variables
The variable that the experimenter changes to see its effect on another variable
Independent Variable
A hypothesis is
a prediction of what will happen in the experiment and is supported with scientific reasoning
The units for mass are
grams (g)
True or False: substances (of the same material) of the same type all have the same density.
True
mass (g)
The dependent variable is the variable that is
observed and measured
"If the amount of sunlight increases, then the plant's growth will increase."
What is missing from this hypothesis?
Scientific reasoning
The units for volume are
cm3
What is the formula for density and what are the units for density?
Density = mass divided by volume
Units = g cm-3
To accurately measure the volume of liquids, we use
a graduated cylinder
In order for an experiment to be valid, these must remain constant.
Controlled variables
A hypothesis is only valid if controlled variables remain
the same/constant
Why do we always do at least 3 readings of an experiment?
In order to have more accurate results and avoid random error.
Density is a physical property of a substance (material), not an object. Density is the amount of matter in every unit volume so it does not depend on what size the object is.
A beaker is used for
Containing and pouring liquids
Lemon trees receiving the most water produced the most lemons. What is the independent variable and dependent variable?
Independent: amount of water
Dependent: number of lemons
Specific and testable.
In "If...then..because..." format.
How do you find the average of the following data: 5, 7, 3.
(5 + 7 + 3) divide by 3 = 5
An object has a mass of 25g and a volume of 5cm3. What is its density?
25g divided by 5cm3 = 5g cm-3
In order to have an accurate measurement using an electronic balance, you must ensure the starting value is set to 0.00g or ...
You must subtract the starting value from the final value
Lemon trees receiving the most water produced the most lemons. Name 3 controlled variables.
Same type and age of lemon tree, grown in the same environment, same amount of sunlight, Lemons are picked at the same time,
Tony is interested in the following research question: What effect does the amount of plant food (fertilizer) have on plant growth?
What is his hypothesis?
If there is an increase in plant food, then the plant's growth will increase because plants also need nutrients to survive and grow.
An experiment was conducted to find the volume of a glass cube through water displacement. How did the experimenter find the final volume of the glass cube?
2. They measure the V1 (volume with glass cube) of water after the glass cube is placed in the water.
3. In order to find the volume of the glass cube, they subtract V0 from V1.
V = V1 - V0
How can we use density to determine if something can float on water?
If the object has a density below 1g cm-3 then it can float on water because it is less dense than water. If the object has a density above 1g cm-3 then it will sink because it is more dense than water.
In order to avoid parallax error when reading a volume measurement from a graduated cylinder, the experimenter must:
1. Be at eye level of the measurement
2. Measure at the bottom of the meniscus