# Search results

1. ### DIRE NEED of HELP on HARDEST Physics Problem Ever

Ok, so I am in the middle of what is known as the "axe hunt" at my school. It is the culminating event of the year. The seniors puts together a scavenger hunt that is supposed to take 24 hours consisting of various clues that will require juniors to use their athletic and intellectual...
2. ### Spring SHM Problem

1. Homework Statement Two blocks of mass M2 and M1 (M2>M1) are connected by a spring with force constant k and are free to slide on a frictionless table. They are pulled apart and then released from rest. In terms of M1, M2, and k, what would the period of oscillation be? 2. Homework...
3. ### A Few Questions About SHM

I have been doing quite a few SHM problems, and I just have a few questions in general. A lot of questions evolved from one particular problem type: A mass attached to the end of a vertical spring of spring constant k. My questions: 1. How can we prove that we can use the equation...
4. ### Proof of w=(k/m)^(1/2)

So I am attempting to prove the simple harmonic motion equations with calculus so as to develop a better understanding of shm problems and have more flexibility when it comes to solving them. I am having a bit of trouble understanding the proof of w=(k/m)^(1/2) Here is how I am doing it. I...
5. ### Direction of Rolling/Sliding Friction

This much more of a general question that I've encountered in quite a few problems and I haven't found an answer to in my books or searching the net yet. Take, for example, a ball that has been propelled into motion by a spring gun on the floor. Initially, the ball accelerates so that the ball...
6. ### Graph of Kinetic Energy v. Displacement of a Falling Object

[solved] Graph of Kinetic Energy v. Displacement of a Falling Object 1. Homework Statement Draw and label a graph with energy for the y axis and displacement for the x axis of the kinetic energy and potential energy of an object in free-fall that started with a horizontal speed of 30 m/s from...
7. ### Gravitational potential energy

[SOLVED] Gravitational potential energy edit: solved
8. ### Direction of angular acceleration

1. Homework Statement Imagine a car driving on the XY plane in the +y-direction. If it is slowing down, in what direction is the angular acceleration of the wheels? (a) the +x-direction (b) the -x-direction (c) the +y-direction (d) the -y-direction (e) the +z-direction 2. Homework Equations...
9. ### Moment of inertia of a merry-go-round

In a certain problem I was working on, it asks for the inertia of a merry-go-round, and my first instinct was that it would be the inertia of a disk about its central axis I=(1/2)MR^2, but the solution actually uses I = MR^2 the rotational inertia of a hoop about the central axis. Why do they...
10. ### Linear momentum bullet problem

yeah, part c was for the block :) ahh..I thought I had the right answer originally but it didn't say if variables were supposed to be left in the problem, so I kind of doubted myself. Thanks for the help you guys. I am learng physixguru, maybe slowly, but learning. lol
11. ### Physical pendulum oscillation

1. Homework Statement A physical pendulum consists of a meter stick that is pivoted at a small hole drilled through the stick a distance d from the 50 cm mark. The period of oscillation is 2.5 s. Find d 2. Homework Equations T=2PI*sqrt(I/mgh) I(com)=(1/2)mL^2 parallel axis theorem...

1. Homework Statement A girl of mass M stands on the rim of a frictionless merry-go-round of radius R and rotational inertia I that is not moving. She throws a rock of mass m horizontally in a direction that is tangent to the outer edge of the merry-go-round. The speed of the rock, relative...
13. ### Moment of inertia cylinder problem

1. Homework Statement A bucket of water of mass 20 kg is suspended by a rope wrapped around a windlass in the form of a solid cylinder 0.2 m in diameter, also of mass 20 kg. The cylinder is pivoted on a frictionless axle through its center. The bucket is released from rest at the top of a...
14. ### Equilibrium problem involving wierd static friction

This is not necessarily a homework problem, but a sample problem of my book that I do not quite understand. A rock climber with mass m = 55 kg rests during a "chimney climb," pressing only with her shoulders and feet against the walls of a fissure of width w = 1.0 m. Her center of mass is a...
15. ### Equilibrium Ball attached to wall problem

1. Homework Statement A uniform sphere of mass m and radius r is held in place by a massless rope attached to a frictionless wall a distance L above the center of the sphere. Find (a) the tension in the rope and (b) the force on the sphere from the wall. 2. Homework Equations net...
16. ### Completely Inelastic Collision: A block and a block with a spring

I actually have two problems that I have been struggling with that are very similar, so I believe that I am making the same incorrect assumption for both problems, but I am at that point where I have been re-trying the problems for so long that I do not think I am going to find my mistake. 1...
17. ### Gravitation/Average Force Problem

1. Homework Statement What are (a) the speed and (b) the period of a 220 kg satellite in an approximately circular orbit 640 km above the surface of Earth? Suppose the satellite loses mechanical energy at the average rate of 1.4x10^5 J per orbital revolution. Adopting the reasonable...
18. ### Gravitational Potential Energy Problem

[SOLVED] Gravitational Potential Energy Problem 1. Homework Statement Suppose that the moon were at rest at its present distance from the earth, rather than orbiting it. With what speed would it strike the earth? (Take the earth to be infinitely massive relative to the moon) 2...
19. ### 3-dimensional center of mass problem

1. Homework Statement In the ammonia (NH3) molecule, the three hydrogen (H) atoms form an equilateral triangle; the center of the triangle is 9.40x10^(-11) m from each hydrogen atom. The nitrogen (N) atom is at the apex of a pyramid, with the three hydrogen atoms forming the base. The...
20. ### Basic center of mass problem

1. Homework Statement What are (a) the x coordinate and (b) the y coordinate of the center of mass of the three-particle system shown in Fig. 9-22? (c) What happens to the center of mass as the mass of the topmost particle is gradually increased? Fig 9-22 shows a particle at the origin, a...
21. ### Superhard Potential energy/circular motion problem

1. Homework Statement A ball is tied to a cord and set in rotation in a vertical circle. Prove that the tension in the cord at the lowest point exceeds the tension in the cord at the highest point by six times the weight of the ball. 2. Homework Equations U1+K1=U2+K2 F=mv^2/r...
22. ### Spring and Gravity Potential Energies

1. Homework Statement A 2-kg block is dropped from a height of 0.4 m onto a spring force whose constant k is 1960 N/m. Find the maximum distance the spring will be compressed. 2. Homework Equations U1+K1=U2+K2 3. The Attempt at a Solution both the initial and final kinetic...
23. ### Gravitation and the Principle of Superposition

1. Homework Statement How far from Earth must a space prove be along a line toward the Sun, so that that the Sun's gravitational pull on the probe balances the Earth's pull 2. Homework Equations F=Gm1m2/d^2 3. The Attempt at a Solution d1=distance from probe to Earth distance...
24. ### Newton's Law of Gravitation ratio

1. Homework Statement A mass M is split into two parts, m and M - m, which are then separated by a certain distance. What ratio m/M maximizes the magnitude of the gravitational force between the parts? 2. Homework Equations F=Gm1m2/d^2 3. The Attempt at a Solution I first just tried...
25. ### Forces Problem Involving A Tree Branch acting as a monkey's pulley

1. Homework Statement A 10 kg monkey climbs up a massless rope that runs over a frictionless tree limb and back down to a 15 kg package on the ground. (a) What is the magnitude of the least acceleration the monkey must have if it is to lift the package off the ground? If, after the package...
26. ### Tranlastion Motion

1. Homework Statement A red train traveling at 72 km/h and a green train traveling at 144 km/h are headed toward one another along a straight, level track. When they are 950 km apart, each engineer sees the other's train and applies the brakes. The brakes decelerate each train at the rate of...
27. ### Struggling with post-lab question

5. A block of wood floats in a beaker of water. According to Archimedes’ principle, the block experiences an upward buoyant force. If the beaker with the water and floating block were weighed, would the measured weight be less than the sum of the weights of the individual components? Explain...
28. ### Weightless physics question

I have a problem asking me what velocity must be achieved so that a person on at the top of a ferris wheel with a 15-m diameter can feel weightless. I am wondering how you define weightless. At first I tried setting mg=0, but I couldn't get anywhere that way.