Forces and Effects.ppt
- 2. Force •Any push or pull exerted on an object
- 3. System •The object with the force applied
- 5. Contact Force •A force that acts on an object by touching it
- 6. Contact Force •A baseball bat striking a ball
- 7. Long-range Force •A force that acts on an object w/o touching it
- 9. Agent •Whatever is causing the force
- 10. Inertia •The resistance to change (in motion)
- 11. Equilibrium •When the net forces acting on an object = zero
- 12. Force Vector Diagram •A Diagram showing the vectors of all forces acting on an object.
- 13. Force Vector Diagram Weight on table Force of table on the ball
- 14. Draw Force Vector Diagrams of: 1)A book on a desk 2)A book being pushed across the desk 3)A book falling
- 16. Newton’s 1st Law An object will remain at rest or in constant straight-line motion if the net force acting on it is zero
- 17. Newton’s 1st Law The velocity is constant and acceleration is zero when the net force on an object is zero
- 18. Newton’s 2nd Law The acceleration of an object is directly proportioned to the net force applied to it
- 20. Newton’s 2nd Law Fnet = ma
- 21. Newton’s 3rd Law For every action, there is an equal & opposite reaction
- 22. Newton’s 3rd Law FA on B = -FB on A
- 23. Two horizontal forces of 23.5 N & 16.5 N are acting in the same direction on a 2.0 kg object. Calculate: 1) net Force on the object 2) its acceleration
- 24. Two horizontal forces of 23.5 N & 16.5 N are acting in opposite directions on a 2.0 kg object. Calculate: 1) net force on the object 2) its acceleration
- 25. Forces of 4.0 N west & 3.0 N north are acting on a 2.0 kg object. Calculate: 1) net Force on the object 2) its acceleration
- 26. Calculate the acceleration of a 1500 g object falling towards Earth when the Fair friction is 11.7 N.
- 28. Types of Forces Friction Tension Normal Thrust Spring Weight
- 29. Friction (Ff) •The contact force that acts to oppose sliding motion between surfaces •Its direction is parallel & opposite the direction of sliding
- 30. Normal (FN) •The contact force exerted by a surface on an object •Its direction is perpendicular & away from the surface
- 31. Spring (Fsp) •A restoring force, or the push or pull a spring exerts on an object •Its direction is opposite the displacement of an object at the end of a spring
- 32. Tension (FT) • The pull exerted by a string, rope, or cable when attached to a body & pulled taut • Its direction away from the object & parallel to the string at the point of attachment
- 33. Thrust (Fthrust) • A general term for the force that moves rockets, planes, etc • Its direction is the same direction as the acceleration of the object barring any resistive forces
- 34. Weight (Fg) • Force due the gravitational attraction between two objects like an object & the Earth • Its direction is straight down towards the center of the Earth
- 35. Name & describe the 6 types of forces
- 36. Weight (Fg) Weight = Fg = mag = mg Fg = W = mg
- 37. When an object is launched, the only forces action upon it are the forces gravity & air friction.
- 38. No net force is required to keep an object in motion. Frictional forces oppose motion.
- 39. Inertia is not a force, but the resistance to the change in motion or momentum.
- 40. Air exerts huge & balanced frictional forces on an object. When in motion, the net Ff of air is large.
- 41. Terminal Velocity •The constant velocity that is reached when the force of air friction of a falling object equals its weight
- 42. Friction (Ff) Kinetic frictional force Ff, kinetic Static frictional force Ff, static
- 43. Draw Vector Force Diagrams of: 1) a skydiver gaining downward velocity 2) a skydiver at terminal velocity
- 44. Draw Vector Force Diagrams of: 3) a rope pulling a ball up at constant velocity 4) a rope acceleration a ball upwards
- 45. An object’s weight on Earth is 490 N. Calculate: 1) its mass 2) its weight in the moon where gmoon = 1.60 m/s2
- 46. An 500.0 g object on an unknown planet has a weight of 250 N. Calculate the acceleration caused by the planet’s gravity.
- 47. Static Ff •The force exerted on one surface by another when there is no relative motion
- 48. Kinetic Ff •The force exerted on one surface by another when in relative motion
- 49. Forces acting on an object: FN = -W FA > Ff Fapplied Fg or Weight Ff FN
- 50. Static Ff Ff, static = msFN
- 51. m ms is proportionality constant called the frictional coefficient
- 52. Kinetic Ff Ff, kinetic = mkFN
- 53. A 25 N force is required to pull a 50.0 N sled down the road at a constant speed. Calculate the sliding frictional coefficient between the sled & the road.
- 54. A person & a sled have a total weight of 490 N. The sliding frictional coefficient between the sled & the snow is 0.10. Calculate the force required to pull the sled at constant speed.
- 55. Calculate the acceleration of the sled if the applied force pulling on the sled is 299 N. W = 490 N m = 0.10
- 56. Calculate the force required to pull a 500.0 g block with an acceleration of 3.0 m/s2. m = 0.50
- 57. Periodic Motion •Repetitive or vibrational motion like that of a spring, swing or pendulum
- 58. Simple Harmonic Motion •Periodic motion in which the restoring force is directly proportional to the displacement
- 59. Period (T) •The time required to complete one full cycle of motion
- 60. Amplitude •Maximum displacement from the zero point or equilibrium
- 61. Pendulum Motion Formula T = 2p ---- l ag
- 62. Calculate the period of a pendulum with a length of 49 cm:
- 63. Calculate the length of the pendulum of a grandfather clock whose period is equal 1.0 second:
- 65. Calculate the force required to pull a 150 g block at a constant velocity of 180 km/hr. m = 0.20
- 66. A 9.8 kN car went from 0 to 25 m/s in 5.0 s. mK between car & road = 0.20. Calculate the force applied by the engine of the car.
- 67. Calculate the force required to start a 2.0 kg block & its acceleration when moving. ms = 0.20, mk = 0.10
- 68. Calculate the force required to start a 2.0 kg block & calculate its acceleration when moving. ms = 0.20, mk = 0.10
- 69. A 6.0 kg ball is attached by a rope over a pulley to a 4.0 kg ball. 1) Draw the problem. 2) Calculate each ball’s acceleration
- 70. A 6.0 kg ball is attached by a longrope over a pulley to a 4.0 kg ball. 1) Calculate air friction at max velocity
- 71. A 65 kg boy & a 35 kg girl are in a tug-of-war. The girl’s acceleration is 13 cm/s2. Calculate the boy’s acceleration.
- 72. A 150 g baseball, was hit & came to rest in 4.0 s after going 100.0 m. Calculate: vi, a, & Ff on the ball.
- 73. A 50.0 kg box falls off a 0.49 km cliff. 1) Calculate vi, vf, a, & t. 2) Calculate Ff if air friction is included
- 74. A 10.0 kg box falls off a 0.49 km cliff & hits the ground in 20.0 s. 1) Calculate vf & a. 2) Calculate Ff if air friction is included
- 75. Calculate the force required to pull a 250 g block at a constant velocity of 360 km/hr. m = 0.30
- 76. Calculate the force required to accelerate a 1500 g block along the floor at 3.0 m/s2. m = 0.25
- 77. Calculate the apparent weight of a 50.0 kg person on a scale on an elevator descending at 2.0 m/s2.
- 78. Calculate the apparent weight of a 50.0 kg person on a scale on an elevator ascending at 2.0 m/s2.
- 79. Calculate the period of the pendulum on Big Ben which is 4.9 m long.
- 80. Calculate the force required to accelerate a 10.0 kg block straight up at 25 cm/s2.
- 81. Calculate the force required to accelerate a 50.0 kg block straight up over a pulley at 5.0 m/s2.
- 82. Calculate the acceleration of a system of a 55.0 kg block tied to a 45.0 kg block hanging over a pulley.
- 83. Calculate the frictional coefficient of a 100.0 kg block if a 150 N force causes it to accelerate at 50.0 cm/s2.
- 84. Calculate the frictional coefficient of a 10.0 kg block if a 98 N force causes it to slide at 30.0 cm/s.
- 85. A 5.0 N force accelerates a 1000.0 g block at 45.0 cm/s2. Calculate mK.
- 86. Calculate the acceleration of a system of a 200.0 kg cart on a plane tied to a 50.0 kg block hanging over a pulley.