# Week 11

**Read:**Newton's Laws of Motion (ASGv2 Chap. 21); watch all the videos for Chap 21 and for the Force and Rotation Lab!

**Key topics:**newton's laws of motion, force addition, action-reaction pairs, free body diagrams,

**Homework:**

- Momentum and Force (Ex. 21.1),
- Bull-train collision (Ex. 21.2),
- Action-reaction pairs (Ex. 21.3)
__Two astronauts__play tug-of war in outer space. Astronaut A has a mass of 200 kg. Astronaut B has a mass of 150 kg. Astronaut A pulls the rope connecting them with a force of 20 Newtons.

- What is the acceleration of astronaut B?
- What is the force acting on astronaut A?
- What is the acceleration of astronaut A?
- If the rope is 100 meters long when do the astronauts hit each other? Solution.

- A100 gram
__hockey puck__slides across the ice at a speed of 10 m/s due east. A hockey player strikes the puck with a force of 30 Newtons for 0.01 seconds. The force is directed due west. What is the final velocity of the puck after the force is done acting? What if the force, instead was directed due north? Solution.

**Lab:**Force and rotation (Ex. 20.3). You will be guided through the lab by the "Force and Rotation Lab" videos, below. I would recommend that you watch these before coming to lab.

**Chapter 21 (4 videos):**

**Professors Schindler and Kuehn recorded ourselves carrying out this lab in the spring of 2020; watching these videos will lead you through this important and challenging lab exercise.**

Force and Rotation Lab (13 videos):

Force and Rotation Lab (13 videos):