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## 14 October 2009

### Clicker activity -- basics of Newton's Second Law

My wife has been gone for four days. She's hiking with the sophomores on their Outward Bound trip to North Carolina. That means, however, that I'm in charge of six-year-old Milo all by myself. I quite enjoy occasional solo time with the boy. But what to do on Saturday morning, when I had to teach a physics class some more about Newton's Second Law?

I prepared a clicker exercise. Milo loves using the clickers, and he loves being part of a class with juniors and seniors. In turn, the juniors and seniors are welcoming and friendly to Milo -- even moreso due to the "Milo Questions."

I had Milo write a set of multiple choice questions about himself. I promised to use these as part of the in-class activity. Thus, the overall set of questions for the day's clicker exercise consisted of two Newton's Second Law questions, followed by one Milo Question, followed by two more second law questions, etc. The class (including Milo!) was divided randomly into teams; the team that got Milo was excited, because they knew that they had the Milo questions in the bag. As always, each team could collaborate and submit a single answer to each question. They earned one point for a correct answer, and one bonus point for each group who did NOT get the correct answer.

The actual set of questions is below. Feel free to use them. They may sound really easy, but remember how difficult it is to remember and assimilate even the most basic facts about the second law. It takes an amazingly huge number of repetitions before we can break down the most common misconceptions like "motion requires a force" and "acceleration tells which direction something is moving."

(I gave a "fundamentals quiz" about some of these same ideas a few days later. I'll try to post that soon.)

GCJ

1. A bucket whose mass is 10 kg hangs by a rope in which there is 63 N of tension. What is the weight of the bucket?
(A) 100 N
(B) 10 N
(C) 10 kg
(D) 100 kg
(E) 63 N
(F) 63 kg
(G) 73 N
(H) 73 kg
(I) 163 N
(J) 37 N

2. A bucket whose mass is 10 kg hangs by a rope in which there is 63 N of tension. What is the net force on the bucket?
(A) 37 N
(B) 163 N
(C) 100 N
(D) 63 N
(E) The answer depends on which way the bucket is moving.

3. What color is Milo’s house?
(A) Green
(B) Blue
(C) Purple
(D) Yellow
(E) Grey
(F) Brown
(G) White

4. A bucket whose mass is 10 kg hangs by a rope in which there is 63 N of tension. What is the magnitude [i.e. the amount] of the bucket’s acceleration?
(A) 6.3 m/s2
(B) 0.63 m/s2
(C) 3.7 m/s2
(D) 0.37 m/s2
(E) 10 m/s2
(F) 1.0 m/s2

5. A bucket whose mass is 10 kg hangs by a rope in which there is 63 N of tension. What is the direction of the bucket’s acceleration?
(A) Up
(B) Down
(C) The direction of acceleration is unknown

6. What does Milo do after seated meal?
(A) Go out back
(B) Go home
(C) Come here
(D) Go to bed

7. A bucket whose mass is 10 kg hangs by a rope in which there is 63 N of tension. What is the direction of the bucket’s velocity?
(A) Up
(B) Down
(C) The direction of velocity is unknown

8. So how could it possible for the bucket to move upward, then?
(A) The bucket must be slowing down
(B) The bucket must be moving at constant speed
(C) The bucket must be speeding up
(D) The tension has to increase to more than 100 N

9. How many bunnies does Milo have?
(A) 0
(B) 7
(C) 2
(D) 1