www.VirtualNerd.com

How do you solve for the initial velocity of an object that rises and falls near Earth, given time, final position, and initial position?

You try to kick a soccer ball in mid-air, but miss completely. Instead your shoe flies off your foot, goes through the air, and eventually hits your head. Now your head is 1.7 m above the ground, and your shoe starts 1 m above the ground. So what is the shoe's initial velocity if the shoe takes 2 seconds to hit your head?

Summary

  1. yref- reference position
  2. m- meters
  3. yi- initial position
  4. yf- final position
  5. d with an arrow- displacement vector
  6. t- time
  7. a- acceleration
  8. g- acceleration from gravity
  9. vi- initial velocity

Notes

    1. t- time
    2. m- meters, s- seconds
    3. d- displacement
    4. a- acceleration
    5. vi- initial velocity
    1. Remember that gravity always points down towards the earth
    2. a- acceleration
    3. The sign of acceleration is negative because the downward direction is defined to be negative.
    1. vi- initial velocity
    2. d- displacement
    3. a- acceleration
    4. t- time
    1. vi- initial velocity
    2. d- displacement
    3. a- acceleration
    4. t- time
    1. vi- initial velocity
    2. d- displacement
    3. a- acceleration
    4. t- time
    1. vi- initial velocity
    2. m- meters
    3. s- seconds
    1. vi- initial velocity
    2. m- meters
    3. s- seconds