1. The mass of an object and it’s weight are different things. Here we’ll show you how mass, weight, and gravity are all related.

2. Mass is the amount of matter in an object. Mass = The amount of matter in an object

3. If we compare a small boy and a semi truck, the truck contains more matter than the boy, so the truck has a larger mass than the boy. Mass = The amount of matter in an object Smaller Mass Larger Mass

4. Weight is the pull of gravity or force of gravity on an object. For an object on or near Earth, it is the force pulling the object toward Earth. Weight = Force of Gravity Weight

5. If we compare objects on Earth, the more mass an object has, the greater the force of gravity on it, or the greater weight it has. Weight = Force of Gravity Weight

6. In other words, less mass means less weight and more mass means more weight, so the truck has a greater weight than the boy. Weight = Force of Gravity Weight Less mass means less weight More mass means more weight

7. Because weight is a force, it is measured in units of force called newtons, abbreviated with a capital N. Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Weight, or Force of Gravity, in Newtons

8. Weight is equal to mass in kilograms Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Mass in kilograms

9. Times something called the acceleration of gravity, measured in Newtons per Kilogram. Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Acceleration of Gravity in Newtons per Kilogram

10. The value for the acceleration of gravity depends on the mass of the planet or moon the object is on or near. Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Acceleration of Gravity in Newtons per Kilogram Depends on the mass of the planet or moon the object is on or near

11. On Earth, the Acceleration of Gravity is equal to 9.8 newtons per kilogram Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Acceleration of Gravity in Newtons per Kilogram Depends on the mass of the planet or moon the object is on or near On Earth, the Acceleration of Gravity = 9.8 N/kg

12. We can use a capital W to stand for weight. Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Wmg

13. A lower case m to stand for mass, Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Wmg

14. And a lower case g to stand for acceleration of gravity. Weight (N) = Mass (kg) × Acceleration of Gravity (N/kg) Wmg

15. Mass (kg) So now, we can just use these letters to give us an abbreviated form of this equation (click) Weight (N) = × Acceleration of Gravity (N/kg) = Wmg =

16. The equation is W = m times g = × W m g

17. Where W stands for the weight in newtons, = × W m g Weight in Newtons (N)

18. M stands for the mass in kilograms, = × W m g Weight in Newtons (N) Mass in kilograms (kg)

19. And g stands for the acceleration of gravity in newtons per kilogram. = × W m g Weight in Newtons (N) Mass in kilograms (kg) Acceleration of Gravity (N/kg)

20. Here’s an example question. We’re given that a black bear has a mass of 190 kg. A black bear has a mass of 190 kg. What is its weight?

21. And we’re asked for its weight. A black bear has a mass of 190 kg. What is its weight?

22. It is important to know that for any questions involving mass and weight, if you are not told otherwise, assume that the object in question in on the surface of Earth. A black bear has a mass of 190 kg. What is its weight? Unless otherwise told, assume that the object in question is on Earth’s surface.

23. We’re asked to calculate weight and we’re given mass, so we use the equation W = m times g, where W is the weight in newtons, m is the mass in kg, and g is the acceleration of gravity in N/kg. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg)

24. The question tells us that the bear has a mass of 190 kg. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg)

25. So we can substitute 190 kg in for mass A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W (N) 190 kg g (N/kg)

26. It is known that the value for g on Earth is 9.8 newtons per kilogram. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg g (N/kg) “g” on Earth is 9.8 N/kg

27. kg So we can substitute 9.8 newtons per kilogram in for “g” in this equation. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N “g” on Earth is 9.8 N/kg

28. kg 190 times 9.8 is equal to 1862, A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N W 1862 N =

29. kg we see that the unit kilograms is in the numerator and the denominator. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N W 1862 N = The unit kg is in the numerator and the denominator

30. kg so they can be cancelled out, A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N W 1862 N = Can be cancelled out

31. kg leaving us with only newtons as a unit. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N W 1862 N =

32. kg So the unit for our answer is newtons. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N W 1862 N =

33. kg So W is equal to 1862 newtons. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N W 1862 N =

34. kg And we can state the final answer as the weight of a 190 kg bear is 1862 newtons. A black bear has a mass of 190 kg. What is its weight? = × W (N) m (kg) g (N/kg) = × W 190 kg 9.8 N W 1862 N = The weight of a 190 kg bear is 1862 N