Warmup #6

L15 Projectile Motion I

Course

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IN:
The first three questions refer to the material you were to read in preparation for the lesson. Questions one and two require you to write a three or four sentence response. Number three is a multiple choice question. Click in the appropriate circle. Questions 4 is your opportunity to suggest what we should emphasize today and how.

You may change your mind as often as you wish. When you are satisfied with your responses, click the SUBMIT button at the bottom of this page.


1. A man drops a baseball from the edge of a roof of a building. At exactly the same time another man shoots a baseball vertically up towards the man on the roof in such a way that the ball just barely reaches the roof. Does the ball from the roof reach the ground before the ball from the ground reaches the roof, or is it the other way around?




2. A football is kicked at ground level in such a way that the horizontal component of its initial velocity is 7 m/s, while the vertical component is 10 m/s. When it returns to the ground the football will have a speed of about

  1. 17 m/s.
  2. 7 m/s.
  3. 12 m/s.
  4. It cannot be determined from the data.



3. A high-jumper and a long-jumper are both human projectiles, but with slightly different goals. The high jumper wants to travel over a bar without touching it and the long-jumper wants to travel as great a distance as possible without touching the ground.

  1. The high jumpers approach the bar at a moderate forward velocity. They then jump directly upward (obtaining a purely upward force from the ground). Why is the initial horizontal velocity important?

  2. The long jumpers approach the jumping pit at peak sprint speed. They then jump directly upward (obtaining a purely upward force from the ground). Why don't they use all their strength to push forward instead of upwards?

Question taken from "How Things Work: The Physics of Everyday Life (p. 73), Louis A. Bloomfield, John Wiley & Sons, New York (1997).




4. Below is a space for your thoughts, including general comments about today's assignment (what seemed impossible, what reading didn't make sense, what we should spend class time on, what was "cool", etc.):




You may change your mind as often as you wish. When you are satisfied with your responses, click the SUBMIT button.

I received no help from anyone on this assignment.