Linear Kinematics Acceleration Contents Definition of acceleration Acceleration

  • Slides: 21
Download presentation
Linear Kinematics - Acceleration Contents: • Definition of acceleration • Acceleration • Example |

Linear Kinematics - Acceleration Contents: • Definition of acceleration • Acceleration • Example | Whiteboard

Physics Quantities: x - Displacement - Distance and direction v - Velocity - Speed

Physics Quantities: x - Displacement - Distance and direction v - Velocity - Speed and direction t - Elapsed time - -4 m 0 m +4 m x = +5 m + x = -6 m Show velocity + and Meter sticks/car/volvo at intersection In our world, there are two directions + and -

Whiteboards: + or - Velocity 1|2|3 TOC

Whiteboards: + or - Velocity 1|2|3 TOC

A car has a velocity of -2. 4 m/s for 36 seconds. What is

A car has a velocity of -2. 4 m/s for 36 seconds. What is its displacement in this time, and if it started at a position of +127. 0 m, where will it end up? v = x/ t x = (-2. 4 m/s)(36 s) = -86. 4 m (-86 m) So we are at 127. 0 + -86. 4 = 40. 6 m (41 m) displacement -86 m, end up at 41 m W

A train starts at a position of -35. 1 m and ends at a

A train starts at a position of -35. 1 m and ends at a position of 12. 5 m in a time of 13. 8 seconds. What was its velocity during this time? v = x/ t x = 12. 5 - -35. 1 = +47. 6 m v = (47. 6 m)/(13. 8 s) = 3. 449275362 m/s 3. 45 m/s +3. 45 m/s W

A train has a velocity of -25. 2 m/s and ends up at a

A train has a velocity of -25. 2 m/s and ends up at a position of -57 m after a time interval of 15 seconds. What was its displacement during this time, and where did it start? v = x/ t x = (-25. 2 m/s)(15 s) = -378 m (-380 m) Since it moved -378 m, it must have started + 378 m from -57 m, so it started at 321 m. (+320 m) -380 m, +320 m W

Linear Kinematics v = x/t - time rate change of position (m/s) a =

Linear Kinematics v = x/t - time rate change of position (m/s) a = v/t - time rate change of velocity (m/s/s) v - Change in velocity (in m/s) a - acceleration (in m/s/s) Example: A car goes from 0 to 27 m/s in 9. 0 seconds, what is its acceleration? (show math, units, meaning, m/s/s, m/s 2, ms-2) a = v/t, a = (27 m/s)/(9. 0 s) = 3. 0 m/s/s TOC

Example: a = v/t A rocket accelerates at 4. 5 “g” s. What time

Example: a = v/t A rocket accelerates at 4. 5 “g” s. What time will it take to reach the speed of sound (Mach I = 343 m/s) from rest? 1 “g” = 9. 81 m/s/s so 4. 5 “g”s = (4. 5)(9. 81 m/s/s) = 44. 145 m/s/s a = v/t, 44. 145 m/s/s = (343 m/s)/t t = 7. 7698… t = 7. 8 s TOC

Whiteboards: Acceleration 1|2|3|4|5 TOC

Whiteboards: Acceleration 1|2|3|4|5 TOC

A car speeds up from 0 to 21 m/s in 5. 3 seconds. What

A car speeds up from 0 to 21 m/s in 5. 3 seconds. What is their acceleration? a = v/ t a = (21 m/s)/(5. 3 s) = 3. 962264151 m/s/s 4. 0 m/s/s W

A train can accelerate at. 15 m/s/s. What time will it take to reach

A train can accelerate at. 15 m/s/s. What time will it take to reach its top speed of 24 m/s from rest? a = v/ t v = 24 m/s, a =. 15 m/s/s, . : . t = 160 s W

What is the final speed if a person accelerates from rest at 32 f/s/s

What is the final speed if a person accelerates from rest at 32 f/s/s for 2. 7 seconds? a = v/ t t = 2. 7 s, a = 32 f/s/s, . : . v = 86. 4 f/s 86 f/s W

What is your acceleration if your velocity goes from 35 m/s to 20. m/s

What is your acceleration if your velocity goes from 35 m/s to 20. m/s in 4. 7 seconds? a = v/ t v = -15 m/s, t = 4. 7 s, . : . a = -3. 1915 -3. 2 m/s/s W

What is your final velocity if you are going 12 m/s and you accelerate

What is your final velocity if you are going 12 m/s and you accelerate at. 48 m/s/s for the next 16 seconds? a = v/ t a =. 48 m/s/s, t = 16 s, . : . v = 7. 68 m/s 12 m/s + 7. 68 m/s = 19. 68 m/s 20. m/s W

Consider the last problem: 12 m/s + 7. 68 m/s = 19. 68 m/s

Consider the last problem: 12 m/s + 7. 68 m/s = 19. 68 m/s vi + at = vf New formula: vf = vi + at vi - initial velocity vf - final velocity a - acceleration t = time elapsed Show + and - acceleration with + and – velocity cars have a + and – accelerator pedal what happens when you get that wrong…. . TOC

Whiteboards: vf = vi + at 1|2|3|4|5 TOC

Whiteboards: vf = vi + at 1|2|3|4|5 TOC

A car going 24. 8 m/s decelerates at -2. 451 m/s/s for 1. 67

A car going 24. 8 m/s decelerates at -2. 451 m/s/s for 1. 67 s. What is its final velocity? vf = vi + at vi = 24. 8 m/s, a = -2. 451 m/s/s, t = 1. 67 s. : . vf = 20. 707 m/s 20. 7 m/s W

What is the acceleration of a ball that goes from 12. 5 m/s to

What is the acceleration of a ball that goes from 12. 5 m/s to 17. 8 m/s in 2. 5 seconds? vf = vi + at vi = 12. 5 m/s, vf = 17. 8 m/s, t = 2. 5 s. : . a = 2. 12 m/s/s 2. 1 m/s/s W

A cop clocks a car going 22. 4 m/s after having accelerated at -7.

A cop clocks a car going 22. 4 m/s after having accelerated at -7. 45 m/s/s for the last 3. 4 seconds. What was the initial velocity of the car? vf = vi + at vf = 22. 4 m/s, a = -7. 45 m/s/s, t = 3. 4 s. : . vi = 47. 73 m/s 48 m/s W

What time will it take a train to slow from 23. 2 m/s to

What time will it take a train to slow from 23. 2 m/s to 14. 8 m/s if the acceleration is -1. 2 m/s/s? vf = vi + at vi = 23. 2 m/s, vf = 14. 8 m/s, a = -1. 2 m/s/s, . : . t = 7 s 7. 0 s W

A pitcher throws a ball at a velocity at +34. 2 m/s. The batter

A pitcher throws a ball at a velocity at +34. 2 m/s. The batter does a line drive, giving the ball a velocity of -45. 1 m/s. If the ball was in contact with the bat for. 2153 seconds, what was its acceleration during that time? vf = vi + at vi = +34. 2 m/s, vf = -45. 1 m/s, t =. 2153 s, . : . a = -368. 32327 m/s/s -368 m/s/s W