P195
Bill Bryson's, A Short History of Nearly Everything
There are two independent motions to consider
The motion in the x-direction and the motion in the y-direction.
A. Which motion has no forces acting on it?
B. Which motion does have a force acting on it?
Is this the true motion?
Question #1
Suppose that you are running at a constant velocity and you wish to throw a ball such that you will catch it as it comes back down. In what direction should you throw the ball relative to you?
a. straight up.
b. at an angle to the ground that depends on your running speed.
c. in the forward direction.
Question #2
An airplane flying at a constant horizontal velocity drops a package of supplies to a scientific mission in the Antarctic. If air resistance is negligibly small, the path of this package, as observed by a person in the plane, is a
a. parabola.
b. straight line downward.
c. straight line pointing ahead of the plane.
d. straight line pointing behind the plane.
Question #3
As a projectile thrown upward moves in its parabolic path, at what point along its path are the velocity and the acceleration vectors for the projectile perpendicular to each other? And, parallel to each other?
a. nowhere. b. the highest point. c. the launch point?
When we were kids back in Nebraska, my brother Jim was able to distract me by throwing one snowball really high and then throwing another really low. Both hit me! Why?
The SnowBall Fight
How far?
Rank the launch angles for the five paths
with respect to time of flight, from the
shortest time of flight to the longest.
I, II
