1. Earth’s Force Questions And Answers Popham 6 Science Dr. Browne

2. 1. WHAT IS A FORCE?

3. 1. What is a force? A force is a push or pull There are two main types of forces balanced and unbalanced

4. 2. UNIT TO MEASURE FORCES? INSTRUMENT?

5. 2. Unit to measure forces? Instrument? The unit to measure forces is a Newton (N) Instrument = Spring scale Spring scales can show both weight and friction in N

6. 3. THE AFFECT OF BALANCED FORCES?

7. 3. The affect of balanced forces? Balanced forces are equal in size and opposite in direction. Balanced forces DO NOT cause motion. The object will be at rest. Net force = Zero Newtons 0 N

8. 4. What kind of force cause motion?

9. 4. What kinds of force cause motion? Unbalanced forces cause motion to occur.

10. 5. HOW DO UNBALANCED FORCE CAUSE A CHANGE IN MOTION?

11. 5. How do unbalanced force cause a change in motion? Unbalanced forces can cause: An object at rest to move An object in motion to speed up An object in motion to slow down An object to change direction An object to stop its motion

12. 6. HOW ARE NET FORCES CALCULATED? DIAGRAMED?

13. 6. How are NET forces calculated? Diagramed? Net force is calculated by adding together forces acting in the same direction and subtracting forces acting in opposite directions. Forces are diagrammed using arrows or vectors The resultant vector is an arrow that represents the net for acting on an object 15 N

14. 7. WHAT IS GRAVITY?

15. 7. What is gravity? Gravity is the force of attraction between all objects in the universe On Earth, gravity pulls objects towards Earth’s dense core Gravity on Earth = 9.8 m/s 2

16. 8. WHAT IS NEWTON’S LAW OF UNIVERSAL GRAVITATION?

17. 8. Newton’s Law of Universal Gravitation? The law of universal gravitation states that every object in the universe is affected by gravity.

18. 9. WHAT ARE THE 2 FACTORS AFFECTING GRAVITY?

19. 9. The two characteristics that affect gravity? Mass and distance affect gravity Objects with larger mass have more matter for gravity to pull on Objects farther apart have less attraction between them

20. 10. WEIGHT AND GRAVITY? WEIGHT AND MASS?

21. 10. Weight and gravity? Weight and Mass? Weight is a measure of the pull of gravity on an object. If gravity changes, weight changes Mass is the amount of matter in an object whereas weight is a measure of the pull of gravity. If gravity changes, mass does NOT Weight = mass x gravity

22. 11. WHAT IS FRICTION?

23. 11. What is friction? Friction is a force that opposes the motion of an object. Friction is affected by the amount of force pushing two surfaces together and the type of surface.

24. 12. WHAT ARE THE DIFFERENT TYPES OF FRICTION?

25. 12. What are the different types of friction? Static Sliding Fluid Rolling

26. 13. HOW CAN FRICTION BE CHANGED?

27. 13. How can friction be changed? By changing: Surface Types Pressure or force between the surfaces Friction can be reduced by using: Lubricants are materials that reduce the amount of friction between two surfaces. Like oil, water, or grease. Wheels – rolling friction is less than sliding friction

28. 14. HOW ARE ORBITS CREATED?

29. 14. How are orbits created? Orbits are created from the two forces acting on the object, the forward motion of the object and the pull of gravity, causing the object to travel an elliptical path in between the two forces Any object that travel around another object in an orbit is known as a satellite. There are both natural and artificial satellites. The farther away the satellite is, the slow and longer the orbital path.

30. 15. WHAT IS PRESSURE?

31. 15. What is pressure? Pressure is the measure of the force applied to a surface. Pressure = Force ÷ Area The SI Unit is the Pascal (Pa) or N/m 2 Pressure can be changed by changing the amount of force applied or the surface area

32. 16. TYPES OF PRESSURE?

33. 16. Types of Pressure? As elevation increases, air pressure decreases As depth increases, water pressure increases