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• Users: Rker
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1. ### Abstract Algebra Proof question

I'm having trouble understanding this statement. Can someone provide an example?

Homework Statement The moment of inertia of a sphere rotating about an axis through its center is (2/5)MR^2, where M is the mass and R is the radius of the sphere. What is the moment of inertia of the sphere about an axis on the edge of the sphere? a. 0.4 MR^2 b. 1.4 MR^2 c. 0.9 MR^2...
3. ### What must the third displacement be?

Oh, okay. Also, when I redrew the graph more accurately, point C actually turned up being positioned more west than point B.
4. ### What must the third displacement be?

Is angle OAB 80 degrees? I tried redrawing the graph on paper, and now I don't think it is.
5. ### A Policeman Chases a Speeder

Thank you for the fairly quick reply. I set the formulas equal to each other and got this: 0 = -4(m/sec^2)t^2 + 22.22(m/sec)t + 11.11m Is that correct so far? And, if so, would I just use the quadratic formula to find positive T?
6. ### A Policeman Chases a Speeder

Homework Statement A car is traveling at 80 km/hr in a school zone. A police car is at rest in the parking lot of the school. It takes the policeman 0.5 sec to react before he begins accelerating after the speeder with an acceleration of 8 m/sec2. (a) How far has each car traveled...
7. ### What must the third displacement be?

That does make things easier to understand, but I'm not even certain that I calculated the angles correctly since my graph is inaccurate. Once I do find the angles for triangle OAC, how will that help me find the angles for CAB?
8. ### What must the third displacement be?

Homework Statement A delivery man travels 35 mi northwest to his first stop, 60 mi in a direction 35° west of south to his second stop. His third stop is supposed to be 100 mi west of his original position. What must his third displacement be (magnitude and direction) for him to reach his...
9. ### Baseball - (2D?) Kinematics - Projectile Motion

Thanks, semc. My homework assignment is due in a few minutes, so I can't type all that I wrote, but I calculated that the fielder must run 13.56 m/sec to catch the ball, which isn't possible.
10. ### Basic Kinematics Questions - What's wrong with my answers?

That makes sense. Thanks. Does anyone know why a field goal is kicked from the ground while a punt is drop kicked. From personal experience, I know accuracy may have something else to do with it, but I have little clue how it relates to kinematics specifically.
11. ### Baseball - (2D?) Kinematics - Projectile Motion

I asked someone else, and he said that I should draw an accurate graph of this problem. But, I wasn't taught how to do this in class. I think my professor just used trigonometry or the equation you suggested, semc. I'm confused...
12. ### Basic Kinematics Questions - What's wrong with my answers?

Oh, okay. I think I understand (b) and (f) now. Acceleration is a vector, which means direction must be considered. And, both rocks will have the same speed before they hit the ground, right? Or, will the rock thrown upward have had more distance to have a higher acceleration (and speed)?
13. ### Basic Kinematics Questions - What's wrong with my answers?

Homework Statement 38. (b) Is it possible to be accelerating if you are traveling at constant speed? Explain your answer. (d) Explain why, in American football, a field goal is kicked from the ground while a punt is drop kicked. (f) Reaching out from a balcony, you throw rock A...
14. ### Free Fall Problem - Please Just Check Work

Homework Statement A bolt comes loose from the bottom of an elevator when it is at a height of 15 m above the bottom of the elevator shaft. If the elevator is originally moving upward at a speed of 7.5 m/sec, assuming that the elevator continues to ascend at a constant speed, how high above...
15. ### Baseball - (2D?) Kinematics - Projectile Motion

Homework Statement A batter hits a baseball at a speed of 45 m/sec at an angle of 50° above the horizontal. The right fielder, who is standing 300 m away from the batter, begins to run when he sees the bat hit the ball. If the fielder runs at a constant speed, what speed does he need to run...