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Quote of the Week From My Life.


Lucius

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A slingshot can be modeled as a single spring used to throw projectiles. Assume a large slingshot can throw a projectile of mass 0.2 kg a distance of 60 meters when it is launched at an angle of 20 degrees above the horizontal. (Questions 1 through 5 are from life; your instructor terrorized campus as an undergraduate, shooting water balloons at deserving targets under cover of night.)

 

1. How much energy is stored in this slingshot just prior to releasing the projectile? (10 points)

2. The spring begins with a length of 1.8 m and is pulled to a length of 5.5 m while getting ready to launch. What is the spring constant of this spring? What tension is in the spring? (20 points)

3. If the spring is a solid cylinder with a diameter of 1 cm, what is Young's modulus for the spring material? (10 points)

 

Suppose that at the instant of launch the projectile (initially a solid sphere) breaks into two equal pieces of 0.1 kg connected by a thin, negligible-mass rod 0.10 m long. In this process, half the kinetic energy of the projectile is transformed into rotational kinetic energy as the "dumbbell" starts spinning around its center.

 

4. With what angular velocity does the "dumbbell" projectile rotate? (10 points)

5. Describe the motion of the center of gravity of the "dumbbell" projectile. How is it different from that of the original spherical projectile? How far from the launch point does the "dumbbell" projectile land? (20 points)

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13: Textbook, chapter 4, problem 52. A north end of a southbound horse move by the instructor, since you need the results of 51 to do 52. You could pinch those from the back of the text, but hopefully you will be able to do this if an exam asks for it....

 

From my posted solutions to a mechanics homework gave about a decade ago.

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I’m waiting at home this week for some workmen who are several hours late to do repairs on the downstairs bathroom.  My brother who’s at work is getting more and more angry at their repeated snow job about being “5 minutes out” keeps texting me about whether they’ve arrived or not. 
  Finally he calls me and says “Maybe they started working and you didn’t hear them, go check.”  I tell him that I’m standing in the bathroom in question.  He then says “Are you sure they’re not there.”  I reply “I may not be too smart, but I know how to count to zero.”

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My eldest son, light of my life, has gone back to college after more than a year hiding from the plague at home. I knew and intended that he would be exposed to different ideas at school, that’s part of what it is for. Meet different people, listen to different music and see different art, and so on. But

 

This child writes me this text yesternight, and I’m still not over it. 
 

“I’m listening to jagged little pill. How did you never play this album for me? This shit rules.


Robin this might be the best album I’ve heard in a long long time.”

 

His mother and I, we did our best. 

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16 minutes ago, BoneDaddy said:

My eldest son, light of my life, has gone back to college after more than a year hiding from the plague at home. I knew and intended that he would be exposed to different ideas at school, that’s part of what it is for. Meet different people, listen to different music and see different art, and so on. But

 

This child writes me this text yesternight, and I’m still not over it. 
 

“I’m listening to jagged little pill. How did you never play this album for me? This shit rules.


Robin this might be the best album I’ve heard in a long long time.”

 

His mother and I, we did our best. 


   I actually like that album.  A little angsty, and kind of dated but I’ve certainly heard worse....Fiona Apple anybody?

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