Mechanics

Q: Pendulum Motion of Text book (In class 2/22 conceptual question). After you explained this question in class I was still confused. How can the book accelerate to the right at the bottom, if the only forces acting on it are pushing it up and down? Trying to rationalize this answer, is this because it […]

Q: I would like to make certain I understand why the ideal rope is removed from the diagrams. Both sides of the rope are being pulled equally, so there is equal and opposite forces on the x axis that cancel out. In the Y axis, the rope would, if it had mass, have a weight

Q: If an object starts at 0 and accelerates to the left to final position 1, why is “a” negative? Is it because the object is going to the left of 0, so it is “negative accelerating?” A: First, the motion (1-D) is toward the left. The velocity is negative according to the sign conventions.

Q: I had a quick question about the particle models. If time stamps are t=1, t=2, t=3, etc. and the velocity vectors 1,2, and 3 are listed between each point, these vectors refer to AVERAGE velocity right? And since average velocity uses displacement between time stamps, a particle in the model could theoretically move back

Q: If velocity is zero, why wouldn’t acceleration be zero as well? Seeing that both velocity and acceleration are related and given that finding the acceleration relies on the velocity, why is the acceleration unknown at a specific time instance if the velocity is known to be zero at that time? A: Acceleration is the

Q: For conservation of momentum, what counts as an external force/impulse? Does gravity count? A: After we have defined the system of interest in a problem, for example, the 2 objects in a 2-body collision, any force/impulse from the outside of the system is considered external! Yes, gravity is external! However, the impulse of gravity

Q: At the beginning of the lecture today when explaining a fixed pulley, you mentioned there being a connection between circular motion and rotation. I am a bit confused about what exactly the relationships are between them and was wondering if you could provide me a bit more clarity about it. A: For a rotating

Q: I was wondering if an object’s linear velocity in a circular motion is always expressed as a magnitude, or if the sign depends on the direction that the object is traveling around the circle (e.g., clockwise/counterclockwise.)  A: In a circular motion, the linear velocity is always in the Tangential direction, but Tangential is actually

Q: This is a conceptual question I have wondered since high school but never asked. If every force has an equal and opposite reaction, then how come a sledgehammer is easily able to crush a grape? Going off of Newton’s third law, shouldn’t we expect to see the grape push back with just as much