Physical Science Review for the NC final exam

1. Physical Science Review for the NC final exam

2. What is determined by the distance from the starting point in a straight line?

3. Answer: Displacement Follow-up Question: List 2 things that make determining the value of displacement different from determining distance values.

4. The stationary object that is used to determine if an object has motion.

5. Answer: Reference point

6. What is the equation used to determine the speed of an object?

7. Answer: V = d t Follow-up Questions: a) What do the v, d, and t symbols represent in the formula? b) What other value can this formula represent, and how is this value different from speed.

8. What is the equation used to determine the acceleration of an object?

9. Answer: a = ( Vf - Vi ) t Follow-up Questions: • What is meant by each of the variables in the equation? • When would the Vf value be zero? • When would the Vi value be zero?

10. What are 2 ways that you could change the acceleration of an object?

11. Answer: You could change the speed of the object or you could change the direction of the object.

12. B D C A What is represented by the velocity/ time line at point A ? What is represented by the velocity/ time line at point B ? What is represented by the velocity/time line at point C ? What is represented by the velocity/time line at point D ?

13. Answer: • Point A = the object is accelerating. This is a constant acceleration as the distance increase occurs at the same distance for each same time interval. • Point B = Since the velocity (speed) does not change, but the time does the object is traveling at a steady speed. • Point C = Since the velocity at point C goes down the speed is decreasing (is negative). • Point D = The upward J shape on the velocity / time graph shows a great jump/increase in velocity over a short time so ( acceleration is increasing)

14. What is the equation for momentum?

15. Answer: P = mv m= mass, v=velocity

16. Explain how a less massive object can have the same momentum as a more massive object.

17. Answer: The less massive object can be traveling at a much faster rate than the more massive object. Ex: 10 kg object moving at 10 m/s= a momentum of (10x10=100 kg m/s) 20 kg object moving at 5 m/s = a momentum of (20x5= 100 kg m/s) They both have the same momentum.

18. Can an object have a momentum of zero?

19. Answer: Yes, it the object is not moving (at rest) the velocity (speed) would be zero. If p=mv and v=o then no matter how big the mass, p=0.

20. Why would you weigh more on Earth than you would on the moon? (Explain using an equation)

21. Answer: Because the formula for weight is Fg = mg ( Weight= mass x gravitational pull ) Because the mass of the Earth is greater than the mass of the moon it has a greater gravitational pull. If the mass (the amount of matter in an object) remains the same and the “ g “ increases so does the weight.

22. What is it called when an object falls with only the force of gravity acting on it?

23. Answer: Free fall Follow-up Question: What is the rate (velocity) at which objects on Earth experience free-fall.

24. When does a falling object reach terminal velocity?

25. Answer: When the acceleration of an object in free fall is equal to the upward force of air resistance. This results in an acceleration of zero.

26. Friction is a force that opposes the motion of an object. List the type of friction in each of the following examples: • A fish swimming in a stream. • A car wheel as a car travels down the road. • A plate sitting on the table. • A wooden crate pushed across the floor.

27. Answer: • The fish is moving in water (a fluid) and therefore the water is exerting fluid friction on the fish. • The car wheel is round and thus as it moves will exhibit rolling friction. • The plate is sitting (thus at rest not moving) on the table. It is therefore encountering static friction. • The wooden crate flat surface is being pushed across the floor. The crate bottom is therefore sliding across the floor and is experiencing “sliding friction”

28. Explain why Newton’s 1st law of motion is also called the law of inertia. Newton’s 1st Law: An object at rest, (or an object in motion), will continue to remain at rest, (or in motion) unless acted on by an unbalanced force.

29. Answer: Inertia= the tendency of an object to resist change. This means that if it is at rest it wishes to remain at rest. If it is in motion is wishes to continue the motion.

30. How does an applied force on an object affect the rate at which the object accelerates?

31. Answer: If the same force is applied on the objects of different masses it will cause them to move at different rates of acceleration. Ex: 20 N of force is applied to two objects. One object is 10 kg, the other has less mass at 5kg. When the same force (20N) is applied to both the larger object moves less (20N = 10 kg x 2 m/s2) than the smaller object (20N = 5 kg x 4m/s2)

32. What is the equation associated with Newton’s 2nd law of motion?

33. Answer: F = m x a

34. Which one of Newton’s laws of motion is demonstrated by firing a rifle?

35. Answer: Newton’s 3rd law of motion. Action-Reaction law (For every action there is an equal and opposite reaction.) The gunpowder explodes the hot gases expand outward allowing the rifle to push the bullet. The bullet pushes backwards upon the rifle.

36. Follow-up Explanation: Why does the bullet move out of the gun barrel if the forces are equal? - Although the forces are equal, they are acting on different objects. The bullet will accelerate from the gun barrel because the mass of the bullet is less than the mass of the rifle.

37. Matter is classified as either a pure substance or a mixture. • List the 2 types of pure substances. • List the 2 types of mixtures.

38. Answer: • Pure Substances include: Elements (found on the periodic table) Compounds • Types Of Mixtures: Heterogeneous (mixtures made of different things that have different properties because the mixture is not uniform throughout) Homogeneous (mixtures in which the parts are mixed and distributed in a uniform matter where all parts of the mixtures appear to contain the same material).

39. List the following as either a pure substance ( P ) or a Mixture (M) • Granite rock • Air • Salad • Blood • Ink • Oil/vinegar salad dressing

40. Answer: • Granite rock ( Hetero) • Air (Homo) • Salad ------ ( Hetero) • Blood ( Homo) • Ink ( Homo ) • Oil/vinegar salad dressing--- (Hetero)

41. All of the following are pure substances. List an ( E ) next to the elements and a ( C ) next to the compounds. • Sulfur C) table salt • Water D) Copper

42. Draw the periodic table and show where the metals, nonmetals and metalloids are located.

43. List the following in order of particle size from smallest to largest particles. • Colloids • Solutions • Suspensions

44. Answer: • Solutions  Colloids  Suspensions Solutions have particles so small and evenly distributed that they may be mistaken as a pure substance. Colloids often have particles permanently suspended within them. It may be necessary to shine a light through them to see the particles “ The Tyndall Effect” Suspensions have particles so large that agitation/ movement is required to keep them in the solution. If allowed to sit without movement the particles will settle out of the solution.

45. List the following elements as a metal (M), nonmetal (NM) or a metalloid (ML). • Calcium e) silicon • Nitrogen f) potassium • Sodium g) chlorine • Antimony h) oxygen

46. Answer: • Calcium (M) e) silicon (ML) • Nitrogen (N) f) potassium (M) • Sodium (M) g) chlorine (N) • Antimony (ML) h) oxygen (N)

47. Give 3 examples of endothermic phase changes.

48. Answer: Melting ( solid  liquid ) Vaporization ( liquid  gas ) Sublimation ( solid  gas ) (dry ice (Frozen CO2)  gas)

49. Give 3 examples of exothermic phase changes.

50. Answer: Condensation ( gas  liquid ) Freezing ( liquid  solid) Deposition ( gas  soild)