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### 69 Multiple choice questions

1. 1. Space objects will move forever once set in motion.
2. Friction and air resistance are the net forces that usually slow objects.
2. the force exerted by a fluid depends on the height of fluid above it; the deeper the object, the more pressure.
3. force is a __________ quantity.
4. µ depends on the _________ of surfaces in contact
5. force of surface on object
1.Perpendicular to surface
2. Acts opposite to gravity
6. long-ranged but weak; attractive or repulsive force between objects carrying electrical charge.
(it's less than your weight in air because FB pushes upward)
8. inertia is a ___________ quantity
9. an object's terminal velocity depends on the object's _____________.
10. mass is ____________; weight depends upon the ___________.
11. SI units for inertia are _____
12. objects don't accelerate downward forever - at some point their velocity becomes _____________.
13. Objects behave as particles
Masses of strings are negligible
Interested only in the forces acting on the object
(neglect reaction forces)
14. objects accelerating _________ seem heavier.
15. If an object's weight > buoyant force, then it ________.
16. acts when the object is in motion; f is constant while in motion
17. a drawing showing all forces on an object
18. a force pushing against a specific area of a surface. (force/area)
19. a human's terminal velocity is about 150 mph; an ant's is so low that it can fall far and not get hurt.
20. a push or pull
21. resistance to motion
22. __________ is a measure of inertia
23. force on a rope
24. *Set the x-axis along the incline and y-axis perpendicular to the incline
*Normal points along y-axis
*Weight points straight down (break into components)
*Friction acts along x-axis
25. weight equation
26. an object at rest stays at rest and object in motion stays in motion unless acted upon by a net external force.
27. ________ scales display the normal force; they are they are the same when a=0.
28. The µs and µk are _____________ of the area of contact
29. objects accelerating ___________ seem lighter.
30. When you apply a force to a confined fluid (a closed system), that pressure is applied equally to all parts of the fluid
31. 1. Every action has an equal and opposite reaction
2. Forces always occur in pairs
3. Action and reaction forces must occur on 2 separate objects
4. Equal in magnitude but opposite in direction
32. acts to keep the object from moving; if Fa increases, so does ƒs
33. the gravitational pull on an object; always points straight down
34. very short range and very weak; responsible for radioactive decay.
35. the tendency of an object to continue in its original motion (or resist change in motion)
36. When the upward Fair resistance = the downward Fgravity, the Fnet = ____.
37. strongest force; attractive force that holds the nuclei of atoms together.
38. F=ma
If a constant force is applied to an object,
it will ACCELERATE
39. describes the relationship between the motion of objects in our everyday world and the forces acting on them
40. The direction of the f is opposite the direction of motion
Friction is proportional to the normal n
f = µ n (fyi 0 < μ < 1)
41. constant speed
42. If an object's weight < buoyant force, then it _______.
43. force units are measured in ____________
44. the sum of all forces on an object
45. *The object is in static equilibrium
*The upward buoyant force is balanced by the downward force of gravity
46. touching
47. always attractive, and acts between all matter in the Universe; weak, but very long ranged; it's the dominant force in the universe for shaping galaxies and stars.
48. 1.Balancing forces involves vector addition.
2.The sum of the forces involves considering x- and y-direction forces.
3.Objects in equilibrium have their forces balanced in both x- and y- directions.
49. acts upward on an object in a fluid making an object feel lighter.
50. the tension on a rope is the __________ at all points on the rope.
51. falling objects have 2 forces on them: What are they?
52. not moving; a=0
53. Pressure is transferred through a fluid.
An applied small Force on a small Area transmits a big Force on a big Area.
Ex: car brakes, car lift
54. constant velocity; a=0
55. static friction (fs) is ___________ than kinetic friction(fk)
56. If the object is more dense than the fluid:
The net force is ______________, so
The object accelerates _________________
57. friction is caused by......
58. The buoyant force on an object equals the weight of water displaced by the object.
59. If the object is less dense than the fluid,
the object experiences a net _____________ force
60. What are the four fundamental forces of nature (field)?
61. Whether an object sinks or floats depends on the .........
62. Means ΣF = 0
there is no acceleration.
(there must be no net torque too)
63. factors of friction
64. non-moving fluids (ex. pressure, floating)
65. gravity, charges, magnets
66. moves fluid by changing the pressure in the fluid
67. a gas or liquid (both flow)
68. If ΣF (net force) = 0, then there is
_______ ACCELERATION.
69. caused by 100 km of air above us