Pre-Lab Questions and Discussion

1. A woman is going to row a boat across the river as shown. She keeps the stern of the boat perpendicular to the shore line as she rows. Draw a line showing the woman's path of motion over the ground for the following three cases:

• case 1: the river has no current
• case 2: the river has a fast current (faster than the boat toward the top of the page
• case 3: the river has a slow (slower than the boat) current to ward the top of the page

2. On another day, the woman is going to meet her friend on the far shore who is in an innertube. The two friends decide to signal each other with mirrors and, on signal, the woman with the boat will begin rowing as her friend in the inner tube jumps into the tube and starts floating down the river. The current is toward the top of the page faster than the boat is able to row.

• Draw the paths of the two friends over the ground as they move across and down the river.
• Mark each path with dots which represent where the person is when the woman rowing the boat is 1/4, 1/2, 3/4, and all of the way across the river.

3. On yet another day, a third friend will be walking across an upstream bridge while the one friend rows across the river and the second friend floats downstream on the inner tube. The friend on the bridge walks at the same speed that the woman rows the boat. Meanwhile, a fourth person rides his bike along the river, talking to the person in the inner tube. The bike rider goes at the same speed as the person in the inner tube.

• Draw the paths of the four people.
• Mark each of the four paths with dots which represent where the person is when the woman rowing the boat is 1/4, 1/2, 3/4, and all of the way way across the river.