Lesson 11 of 12 · Kinematics
Lesson⭐ 30 XPVectors: Adding Motion in Two Directions
Kinematics.
🎯 Your mission
Learn the rule. Then catch nature using it.
⚡ The twist
Nature loves to surprise the careful watcher.
Mind = Blown
🔬 The more you look, the more nature shows you.
Make a hypothesis first
Before you start: write down what you think will happen, and why.
What You'll Learn
Velocities and displacements add head-to-tail, not by simple arithmetic. Swim at 2 m/s across a river flowing at 1.5 m/s and your resultant speed over the ground is 2.5 m/s, from Pythagoras, directed downstream of where you aimed.
Key Words
Tap a word to see its definition.
Steps
Read the explanation above and note the two key terms before you start.
On graph paper, draw a 6 cm arrow east and a 8 cm arrow north head-to-tail. Measure the resultant with a ruler and protractor, then check it against Pythagoras and the tangent ratio. Repeat for two vectors that are not at right angles.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2A swimmer heads across a river at 2 m/s; the current is 1.5 m/s. The resultant speed is:
Where you see this in real life
This shows up in your everyday life more than you'd think.
Stretch Challenge
Try this in real life this week.
Try one experiment in real life this week — even a tiny one.
For the dinner table
“What's the most surprising thing you learned today?”
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Vectors: Adding Motion in Two Directions
Learn the rule. Then catch nature using it.
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