1.  Force Due to Gravity

2. What’s the difference between Mass and Weight?  Mass (m) is the amount of material an object is made from. Also, mass is the resistance to change in motion.  Mass is measured in Kilograms (kg)  Weight is the Force of Gravity applied to that object. Weight (F G ) is measured in Newtons (N).

3. What affects an object’s Weight?  Weight is a force, so it is determined by the:  Mass of the object.  Acceleration due to gravity where the object is located.  Force due to gravity is always directed towards the center of the Planet the object is on/near.

4. Calculating Weight of an Object  Since Weight is a force: F = ma So, F G = ma G F G = mg

5. Practice Problem 1  A 1.2 kg book is resting on a desk. What is the weight of the book? How much force must the desk apply to the book?

6. Practice Problem 2  How much force is required to lift a 20 kg block off of the ground?