I'm presenting four AP Institutes and a one-day workshop in summer 2023 - you can look at the sidebar for details. One of the institutes and the one-day workshop are in person; the other are online. (I also will do a Conceptual Physics Summer Institute if I can get at least 10 people committed - send me an email if you'd like to suggest dates for this!)
One of my emphases for this summer's trainings will be culture building. Yes, I will, as always, show you lab ideas, show you how I teach various topics, give you gigabytes and gigabytes of ready-to-use materials for your classes. This year, I want to be more conscious than ever about discussions of culture in our classrooms. How do we get students to focus on the process of learning physics rather than merely the outcomes of their tests? How do we foster authentic curiosity rather than merely transactional grade grubbing?
Effort in physics is a matter of character, not reward. It is an end in itself, not a means to an end. Many students believe and follow this mantra in their athletic or artistic pursuits. It's a major goal of mine to translate this authentic approach into my physics classroom, and into as many physics classrooms as possible across the world. Come join me, and we can share ideas! (Don't worry, we'll also talk nitty-gritty details of physics teaching, too. :-) )
FUNDAMENTALS CHECK #13
121. A rope pulls with a tension of 100 N at an angle of 20 degrees above the positive x axis. Which has greater magnitude - the x component of this tension, or the y component of this tension?
122. A solid cylinder of mass M and radius R rolls down an incline. Is its rotational inertia about its center greater than, less than, or equal to MR^2?
123. A ball is thrown at an angle above the horizontal. When it is just about to hit the ground, what is the magnitude of the horizontal component of its acceleration?
124. An object moves in a circle at constant speed. Describe the direction of the unbalanced force on the object.
125. An object has mass 100 kg. I take this object to Mars, where the free-fall acceleration is 4/10 that on earth. What is the weight of this object on Mars?
126. Is work a vector or scalar quantity? (That is, does work have a direction, or not have a direction?)
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| Image is for problem 127. |
127. Planet A of mass M and planet B of mass 4M are separated by a distance X. What is the magnitude and direction of the force of planet A on planet B?
128. What is the equation for spring potential energy?
129. Two carts on a horizontal frictionless track collide with each other and stick together, though they keep moving. What forms of energy does the two-cart system possess after the collision? Take the gravitational potential energy to be zero.
130. In one experiment, a felt-covered 1 kg block slides on an aluminum track. The block slides to rest. In a second experiment, an additional 2 kg is placed on top of the block, and the block slides to rest again from the same initial speed. How does the coefficient of friction experienced by the block change in the second experiment?
My answers to fundamentals check 13:
ReplyDelete121. the x-component. (The x-component is 100 N cos 20, while the y-component is 100 N sin 20.)
122. less. (The rotational inertia would be MR^2 if all the mass were located a distance R from the axis of rotation. A solid cylinder has most of its mass less than R from the center! So its rotational inertia is less than MR^2.)
123. zero.
124. toward the center of the circle.
125. 400 N. (On earth, the weight would be 1000 N. On Mars, the weight would be 4/10 of that. The mass is still 100 kg.)
126. scalar. (Does not have direction.)
127. G(M)(4M)/x^2, direction is to the left in the diagram, toward planet A. (Other permutations of this equation are fine, like 4GM^2/x^2, etc.)
128. (1/2)kx^2.
129. kinetic energy and internal energy. (The collision is inelastic, so the energy cannot be all kinetic after collision.)
130. it is unchanged. (The coefficient of friction depends only on the surfaces in contact.)