1. What is the difference between mass and weight?

2. Mass Quantity of matter Measured with a balance
How much “stuff” is there
Measured in grams
Constant

3. Weight Measure of force of gravity Measured with a spring scale
Changes depending on where you are
Measured in Newtons

4. Weight Changes
Weight depends on the mass of the two objects. For Example: Earth is a lot more massive than other planets, therefore the force of gravity pulling us to it is larger, even though we don’t really feel it. Weights change on different planets depending on size. Would we weigh less on the moon, or Earth?

5. The Moon!
Now, would we have a different mass reading for both places?

6. What is the difference between temperature and heat?

7. Temperature vs. Heat
Temperature: measure of average kinetic energy of particles
Heat: a form of energy that can change the movement of particles, or increase the temp.

8. Temperature Measured in Celsius degree or Kelvin in Chemistry
Measured with a thermometer

9. Heat Results from temperature difference
Measured in joules or calories
Measured with a calorimeter

10. Let’s Look at These Closer..
Place one hand on the top of your desk, and one hand on the leg of the desk. Which feels colder?

11. Probably the Metal, but why?
Metal is a great conductor. It will steal warm energy from your body and move it throughout the metal. The heat is spread out and therefore makes the desk appear colder.

12. Is the metal actually colder?
No, it has been in the same room as the top all day, so they both have the same temperature, just a different way of adjusting to the temperature of your body when your hands are placed on both materials.

13. Why does it take your energy?
The desk is trying to reach equilibrium between your body temperature and the temperature that it is in the room.
Heat always flows from a warmer region to a cooler region.

14. What is the difference between accuracy and precision?

15. Accuracy how closely a measurement matches the true or actual values
only requires the true value (bulls eye) & one measurement (for the arrow to hit the target)
Highly accurate data can be costly and difficult to acquire

16. Precision
the reproducibility of the measurement and how close each measurement is to each other
To be precise, you need several measurements (notice multiple arrow holes), and you do not need to know the true value (none of the values are close to the target but all the holes are close together.)

17. Accuracy & Precision
In order to be accurate and precise, a person would need to receive the same results every time as well as “hit the target”.

18. Comparing Accuracy & Precision
Notice the difference in these pictures.
To win the tournament the archers must hit the target the most times. The winner must show accuracy & precision.
The 1st archer has _____ accuracy & ____ precision.
The 2nd archer has _____ accuracy & ____ precision.
The 3rd archer has _____ accuracy & ____ precision.
The 4th archer has _____ accuracy & _____ precision
BAD
BAD
BAD
GOOD
GOOD
GOOD
GOOD
BAD

19. Example 1
A sample is known to weigh g. Jane weighed the sample five different times with the resulting data. Which measurement was the most accurate?
3.200 g
3.180 g
3.152 g
3.189 g

20. Example 2
Consider the data (in cm) for the length of an object as measured by three students. The length is known to be 14.5 cm. Which student had the most precise work, and which student had the most accurate work?
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Student A
14.8
14.7
Student B
14.2
14.6
Student C
14.4
14.5

22. Percent Error
Percent error: a measure of the accuracy of a measurement
A low percent error means the number is close to the actual (accepted) number
A high percent error means the number is not accurate because it is far from the actual (accepted) number
𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝐸𝑟𝑟𝑜𝑟= 𝑦𝑜𝑢𝑟 𝑣𝑎𝑙𝑢𝑒−𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒 𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒 𝑥 100

23. A student measures the molar mass of carbon to be 11. 8g
A student measures the molar mass of carbon to be 11.8g. If the actual molar mass of carbon is 12.00g what is the percent error of the student’s measurement?