Free Fall Questions Review Example 1 Falling from

Constant acceleration equations a = const v = at + vo x = ½

Falling Objects • “Free-fall” means gravity only force. • ALWAYS accelerating down at 9.

Falling Objects – 1 -way (down positive) • Example 2 -10 – falling from

Falling Objects – 2 -way • Example 2 -12 / 2 -14 – thrown

Falling Objects – 2 -way (down negative) • Example 2 -12 / 2 -14

Falling Objects – 2 -way Asymmetric • Example 2 -14 thrown 1 m up

Other examples • Problem 41 • Problem 46 • Problem 49

Slides: 9

Download presentation

Free Fall • • • Questions / Review Example 1 – Falling from tower Example 2 – Thrown downward from tower Example 3 – Ball thrown upward – symmetric. Example 4 – Ball thrown upward – asymmetric.

Constant acceleration equations a = const v = at + vo x = ½ at 2 +vot + xo v 2 = vo 2 + 2 a x

Falling Objects • “Free-fall” means gravity only force. • ALWAYS accelerating down at 9. 8 m/s 2 – Moment leaves hand – moment hits ground • Sign convention important! – – – y, v, a, must agree Usually (+) up, (-) down If (–) down be consistent Do positive and negative contributions make sense? Example 2 -10, 2 -11 review

Falling Objects – 1 -way (down positive) • Example 2 -10 – falling from tower time accel velocity distance 0+ s 9. 8 m/s 2 0 m/s 0 m 1 s 9. 8 m/s 2 9. 8 m/s 4. 9 m 2 s 9. 8 m/s 2 19. 6 m/s 19. 6 m 3 s 9. 8 m/s 2 29. 4 m/s 44. 1 m • Example 2 -11 – falling with vo = 3 m/s time accel velocity distance 0+ s 9. 8 m/s 2 3 m/s 0 m 1 s 9. 8 m/s 2 12. 8 m/s 7. 9 m 2 s 9. 8 m/s 2 22. 6 m/s 25. 6 m 3 s 9. 8 m/s 2 32. 4 m/s 53. 1 m

Falling Objects – 2 -way • Example 2 -12 / 2 -14 – thrown upward vo = +15 m/s – (+) up (-) down! – Initial velocity, position – Velocity, position at 1 s. Velocity position 2 s – Time to zero velocity. Max height. – Velocity, position at 4 s. – Time to hand, velocity. – Symmetry of problem • Time from bottom to top & top to bottom

Falling Objects – 2 -way (down negative) • Example 2 -12 / 2 -14 – thrown upward vo = +15 m/s time accel velocity distance 0 s -9. 8 m/s 2 +15 m/s 0 m 1 s -9. 8 m/s 2 + 5. 2 m/s 10. 1 m 1. 53 s -9. 8 m/s 2 0 m/s 11. 48 m 2 s -9. 8 m/s 2 - 4. 6 m/s 10. 4 m 3. 06 s -9. 8 m/s 2 - 15 m/s 0 m 4 s -9. 8 m/s 2 -24. 2 m/s -18. 4 m (off scale) – Symmetry of problem • Time from bottom to top & top to bottom

Falling Objects – 2 -way Asymmetric • Example 2 -14 thrown 1 m up 15 m/s – – – – Initial velocity, position Velocity, position at 1 s. Velocity position 2 s Time to zero velocity. Max height without time. Velocity, position at 4 s. Time to ground Non-physical solution if clocks ran backwards

Falling Objects – 2 -way Asymmetric •

Other examples • Problem 41 • Problem 46 • Problem 49