# Search results

1. ### Speed at Which Point Charge in Approaching origin / loss of charge at constant rate

a)Point charge Q = +7.25 μC is fixed at the origin. Point charge q = +1.60 μC is now carefully placed on the positive y-axis, and it floats at (0,7.88). Find the mass of q. b) Refer to question a. Suppose that, as charge q is floating, the point charge Q at the origin begins to lose its...
2. ### Pressure, Volume and Temp Change WORK done?

Pressure, Volume and Temp Change...WORK done??? n = 9.95 moles of an ideal gas are slowly heated from initial pressure P1 = .922 atm and initial volume V1 = 679 L to final pressure Pf = 1.16 atm and final volume Vf = 1073 L. Find T1, the initial temperature of the gas. If the plot of this...
3. ### Thermodynamics, calculating W

n = 9.95 moles of ideal gas are slowly heated from initial pressure Po = 93398.6 Pa and initial volume Vo = .679 m^3 to final pressure Pf = 117508 Pa and final volume Vf = 1.073 m^3. If the plot of this process on a P-V diagram is a straight line, find W, the work done on the system: If the...
4. ### Thermodynamics problem - need to find amount of water that boils

Thermodynamics problem -- need to find amount of water that boils Suppose molten (liquid) lead, mass = 10.28 kg, is at its melting point. The lead is poured into water of mass = 658 g and initial temperature T = 18.7 degrees C. Find the amount of the water that boils. Assume no heat loss. No...
5. ### Angular acceleration and Torque when rod reaches vertical position?

Angular acceleration and Torque when rod reaches vertical position?? A rod (mass 1.30 kg, length .670 m) attached to a frictionless axis is released from rest in the horizontal position. What is the magnitude of the torque and angular acceleration when the rod has reached the vertical...
6. ### Bullet Hits Block Attached to Spring What am I doing wrong?

A wooden block of mass M = 1.83 kg is rest on a frictionless, horizontal table attached to the end of an unstretched spring (k = 217 N/m). A bullet of mass m = 8.02 g is fired horizontally into the block at speed vo = 394 m/s. The bullet comes to rest inside the block, and causes the mass to...
7. ### Buoyany and change in volume underwater

By breathing in deeply, you can change volume of your body. Suppose a swimmer underwater weighs wf = 23.4 N with his lungs full, and we = 48.0 N with lungs empty. Find change in body volume when swimmer inhales. I know the apparent weight = weight in air - buoyant force and buoyant force =...
8. ### Density of Block Submerged into Swimming Pool

A spring is mounted vertically at the bottom of an empty swimming pool. A block of mass M = 857 kg is attached to the spring, and it compresses the spring from its equilibrium position by distance xo. Now the swimming pool is filled with fresh water, and the block is submerged. You find the the...
9. ### Pressure and density

Liquid 1 with density = 6660 kg/m^3 is poured into cylinder to depth d1 = 70.8 cm; Liq. 2 with density 4995 kg/m^3 is poured on top to a depth of 90cm; and then liquid 3 (density of 1369 kg/m^3) is poured on top of liquid 2 to a depth of 68.5cm). Assuming none of the liquids mix at all what is...
10. ### Buoyancy, Volume, Mass

Buoyancy, Volume, Mass..Please Help! a) If 2 boxes have the same apparent weight when submerged in stationary fresh water, and V1 (the volume of box 1) is greater than V2 (the volume of box 2) would the buoyancy of box 1 be greater than box 2 and masses be equal?? If not, would be relationship...
11. ### Weight/Satellite Above Earth's Surface

Satellite of mass 457 kg orbits at 8.44 x 10^6 m above earth. What is weight of 62.3kg man in satellite? Acceleration due to gravity created by Earth at distance of satellite = GMe / r^2 = 1.82m/s^2 ...this is RIGHT. So to get weight of astronaut I multiplied 1.82 by 62.3 = 113N...but...
12. ### Equation for Final velocity: Projectile Fired from Earth

Suppose a projectile is fired upward from the surface of the Earth. If the initial speed of the projectile is v = 12.0 km/s (more than the escape velocity): how fast will it be moving it is so far from Earth that the force of gravity is approximately zero? The equation I was given to solve...
13. ### Equilibrium Ladder Question, can get 1st part but not 2nd

Equilibrium Ladder Question, can get 1st part but not 2nd!! A symmetrical ladder of mass M = 20.8kg leans against a smooth frictionless wall so the top of the ladder is height h = 6.58m above the floor and the bottom of the ladder is distance d = 2.19 m from base of wall. The floor is also...
14. ### Ok then since I am wrong then formula for torque is wrong

Force F is applied to the rim of a uniform disk (M=3.13kg, R=.193m). The disk is mounted on a fixed frictionless axis through its center, and the force is applied at an angle β=45.8° to the radius. The disk starts at rest, and reaches frequency f = 61.1 revolutions per second after rotating...
15. ### Static Friction of hollow sphere rolling up incline

For hollow sphere rolling up incline: I know that the kinetic friction will equal 2/3 acceleration since: μgcosθ=2/3a acceleration = 3/5gsinθ so...kinetic friction = 2/5gsinθ But how I do calculate the force of static friction??
16. ### Velocity of CM of Rod if struck below CM ?

Let's say there is an elastic collision b/t a particle and a rod. The rod (initially motionless) is struck by the particle at some distance below its CM and particle comes to rest. So we have an elastic collision where v of particle is completely transferred to rod. BUT how do I analyze...
17. ### Rot. + Trans. Motion: Conservation of E

Suppose of uniform thin rod (mass M, length b) is attached to a pivot at the top. A piece of clay of mass m strikes the rod at distance x below the pivot at v0 perpendicular to the rod and sticks to it. I understand the E is not conserved b/c this is an inelastic collision (clay sticks to...
18. ### Falling Rod / Linear velocity

A long, thin rod of mass 9.65 kg and length 10.18 cm is standing stright up on a table. Its lower end rotates on a frictionless pivot. A very slight push causes the rod to fall over. What is the speed of the tip of the rod as it hits table? What is speed of center of mass of rod? 1/2 m...
19. ### Rotational Plus Translational Motion for Sphere of Yarn

A massless string is wrapped around the equator of a solid sphere (mass M = 76.2 kg, radius R = 0.211 m). A girl holds the free end of the string, and the sphere is released from rest, Assume: - the sphere is always parallel to the floor - the string is always perpendicular to the radius of...
20. ### Angular acceleration problem / 99% sure I'm doing right but getting wrong answer

A toy car is on a circular track of radius r = .274 m. The car starts at initial speed vo = 1.09 m/s, and accelerates at a constant rate to final speed vf = 2.99 m/s while making 0.507 complete revolutions around the track. What is the angular acceleration? Here is what I did: distance...
21. ### Spring system: Relationship b/t mass and distance object travels

A spring is at the bottom of a frictionless incline. When a box of mass M compresses the spring distance x and is released from rest, the box slides distance d up the incline (measured from where the box is at rest). a) Suppose a box of mass 2M is used to compress the spring distance x,and is...
22. ### Concervation of Momentum: Bullet and Block of Mass

A bullet of mass m = 19.7 g traveling horizontally at speed vo = 445 m/s strikes a block of mass M = 854 g sitting on a frictionless, horizontal table. The bullet comes out the other side of the block at speed v = 415 m/s. What is the speed of the block after the bullet exits the block? Using...
23. ### Center of Mass boat distance from shore what am I doing wrong?

Problem: A symmetrical rowboat, mass M = 116 kg, length L = 6.89 m, points toward the shore. A man, mass m = 90 kg, stands in the back of the boat, distance d = 35.7 m from the shore. If the man now walks to the front of the boat, how far will he be from the shore? Here is what I did...
24. ### Momentum: Nucleus decays into 3

Can someone please help with this one? I'm not sure what to do here. I broke momentum for particles one and two into components (found m1v1cosθ1 + m2v2cosθ2 and m1v1sinθ1 + m2v2sinθ2) but this is not correct and I really don't know what to do. Please help!! A certain nucleus at rest...
25. ### Center of Mass Rowboat Question

Center of Mass Rowboat Question...Please Help! Can someone please help with below question? I really don't know where to begin... When empty, a 166 kg rowboat is symmetrical. A boy of mass 70.5 kg sits 2.1 m from the center of mass of the rowboat toward the front of the boat, and a girl of...