This preview shows page 1. Sign up to view the full content.
3.56. Set Up:
Use coordinates with the origin at the boy and with
downward. The ball has
and
Solve: (a)
The dog must travel horizontally the same distance the ball travels horizontally, so the dog must have
speed
(b)
Use the vertical motion of the ball to find its time in the air.
gives
Then
3.57. Set Up:
Use coordinates with the origin at the boy and with
upward. The ball has
and
Solve: (a)
The dog must travel horizontally the same distance the ball travels horizontally, so the dog must have
speed
(b)
Use the vertical motion of the ball to find its time in the air.
gives
The quadratic formula gives
The negative value is unphysical, so
Then
Reflect:
The ball is in the air longer than when it is thrown horizontally (Problem 3.56), but it doesn’t travel as far
horizontally. The dog doesn’t have to run as far or as fast as in Problem 3.56.
3.58. Set Up:
Use coordinates with
upward. Once the water leaves the cannon it is in freefall and has
and
The water has
and
Solve:
Use the vertical motion to find
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '07
 Shoberg

Click to edit the document details