1. Weight and Mass
Mrs. Wood
4th Grade

2. Index Definitions – 3-4 Newton’s Second Law – 5-6 Weight – 7-9
Mass – 10-14
Examples – 15
YouTube Video – 16
MathCats – 17
Summary – 18
References – 19
Worksheet – 20

3. Weight
The force which is felt by a given mass due to gravity is defined as weight. The weight of an object on Earth, thus depends entirely on the gravity (force of attraction) that is between the object and Earth.

4. Mass Mass is the quantity of matter in an object.
-it’s the “stuff in stuff”

5. Newton’s Second Law
The fundamental relation between the mass and the weight is defined by Newton's Second Law and can be expressed as
F = m a        
~where
F = force (N)
m = mass (kg)
a = acceleration (m/s2)

6. Newton’s Law
This equation helps us understand that if either of the mass increases, the increase in force of attraction will be directly proportional to the mass.

7. Weight
Your weight depends on how much gravity is acting on you at the moment; you'd weigh less on the moon than on Earth, and in interstellar space you'd weigh almost nothing at all.

8. Weight
W=mg
Weight = mass x acceleration (due to gravity)

9. Weight
Spring balance is used to calculate the weight of an object.

10. Mass Mass is often called as weight.
Mass can be measured in both metric and customary units.
Kilogram, gram, and milligram are the metric units whereas ounces and pounds are the customary units

11. Mass
Scale is used to calculate the mass of an object

12. Mass Which object has more mass? a bowling ball or a tennis ball?
a bicycle or a semi-truck?
an egg or a chicken?
If you were in outer space, which one of the above objects would have a greater mass?
If you were in outer space, which one of the above objects would weight more?

13. Mass
Which of the following metric units would you use to measure the weight of a pizza? Choices: A. grams B. millimeters C. seconds D. liters
Correct Answer: A
Grams is used to measure not too small and not too large weights.

14. Mass
Example
-Suppose a sandwich weighs 7 ounces then the same mass in grams is approximately 200 grams. As 1 ounce is about 28 grams then 7 ounce=7× grams.

15. Example Weight versus Mass
A car's mass is 1,644 kg. The weight can be calculated:
w = (1,644 kg)(9.807 m/s2)
    = N
    = 16.1 kN
- there is a force (weight) of 16.1 kN between the car and the earth.

16. Mass vs. Weight Video
YouTube Video

17. Math Cats
Mass and Weight
(click on above)

18. Summary
So basically, the bottom line is that all objects have mass and weight. But, the difference between mass and weight is that mass remains constant no matter where the object is placed in the earth or in the universe. The weight will depend on the place where the object is placed.

19. References

20. Worksheet
Go to the assignment bin and get a worksheet on weight and mass
Get into groups of two
You have 20 minutes to complete the worksheet with your partner
When completed, put the worksheet in the completed assignment bin