Saturday
December 20, 2014

Posts by mymi


Total # Posts: 35

Physics
Water at room temperature flows with a constant speed of 8 m/s through a nozzle with a square cross section, as shown in the figure. Water enters the nozzle at point A and exits the nozzle at point B. The lengths of the sides of the square cross section at A and B are 64 cm ...
November 7, 2011

Physics
The atmosphere of Mars exerts a pressure of only 600 Pa on the surface and has a density of only 0.02 kg/m3. (a) What is the thickness of the Martian atmosphere, assuming the boundary between atmosphere and outer space to be the point where atmospheric pressure drops to 0.01% ...
November 7, 2011

Physics
Two balls of the same volume are released inside a tank filled with water as shown in the figure. The densities of balls A and B are 0.86 g/cm3 and 0.55 g/cm3. (The density of water is 1.00 g/cm3. Take the +y direction to be up. Indicate the direction with the sign of your ...
November 7, 2011

Physics
Two spheres of the same diameter (in air), one of a lead alloy the other one made of steel are submerged at a depth h = 2932 m below the surface of the ocean. The ratio of the volumes of the two spheres at this depth is VSteel(h)/VLead(h) = 1.001206.Knowing the density of ...
November 7, 2011

Physics
A 1.8-g balloon is filled with helium gas. When a mass of 4.8 g is attached to the balloon, the combined mass hangs in static equilibrium in midair. Assuming that the balloon is spherical, what is its diameter? (The density of helium is 0.179 kg/m3, and the density of air is 1...
November 7, 2011

Physics
An airplane is moving through the air at a velocity v = 227 m/s. Streamlines just over the top of the wing are compressed to 80% of their original area, and those under the wing are not compressed at all. (a) Determine the velocity of the air just over the wing. (b) Find the ...
November 7, 2011

physics
Eris, the largest dwarf planet known in the Solar System, has a radius R = 1200 km and an acceleration due to gravity on its surface of magnitude g = 0.77 m/s2. (a) Use these numbers to calculate the escape speed from the surface of Eris. 1360 m/s correct answer. (b) If an ...
October 30, 2011

physics
A carefully designed experiment can measure the gravitational force between masses of 9 kg. Given that the density of iron is 7860 kg/m3, what is the gravitational force between two 9.00-kg iron spheres that are touching? I can determine the correct answer if the problem had ...
October 30, 2011

physics
Newton was holding an apple of mass 120 g and thinking about the gravitational forces exerted on the apple by himself and by the Sun. Calculate the magnitude of the gravitational force acting on the apple due to Newton, the Sun, and the Earth, assuming that the distance from ...
October 30, 2011

physics
In the Earth–Moon system, there is a point where the gravitational forces balance. This point is known as the L1 point where the L stands for Lagrange, a famous French mathematician. Assume that the mass of the Moon is 1/81 that of the Earth. (a) At what point, on a line ...
October 30, 2011

physics
A planet with a mass of (7*10^21) kg is in a circular orbit around a star with a mass of (2*10^30) kg. The planet has an orbital radius of (3*10^10) m. (a) What is the linear orbital velocity of the planet? (b) What is the period of the planet's orbit? (c) What is the ...
October 30, 2011

physics
An asteroid is discovered to have a tiny moon that orbits it in a circular path at a distance of 122 km and with a period of 43 h. The asteroid is roughly spherical (unusual for such a small body) with a radius of 19 km. (a) Find the acceleration of gravity at the surface of ...
October 30, 2011

Physics, need help only on part one.
You are using a 5-m-long ladder to paint the exterior of your house. The point of contact between the ladder and the siding of the house is 4 m above the ground. The ladder has a mass of 18.0 kg. You weigh 56.6 kg and stand three-quarters of the way up the ladder. (a) ...
October 25, 2011

Physics
I got the first part 14.1 kN I just need help with the distance of center of mass behind the front axle.
October 24, 2011

Physics
When only the front wheels of an automobile are on a platform scale, the scale balances at 7.9 kN; when only the rear wheels are on the scale, it balances at 6.2 kN. What is the weight of the automobile? How far is its center of mass behind the front axle? The distance between...
October 24, 2011

Physics
During a picnic, you and two of your friends decide to have a three-way tug-of-war, with three ropes in the middle tied into a knot. Roberta pulls to the west with 412 N of force; Michael pulls to the south with 580 N. In what direction and with what magnitude of force should ...
October 24, 2011

Physics
A 1-kg thin hoop with a 50-cm radius rolls down a 47° slope without slipping. If the hoop starts from rest at the top of the slope, what is its translational velocity after it rolls 16 m along the slope?
October 24, 2011

Physics
A CD has a mass of 15.0 g, an inner diameter of 1.5 cm, and an outer diameter of 11.9 cm. Suppose you toss it, causing it to spin at a rate of 4.5 revolutions per second. (a) Determine the moment of inertia of the CD, approximating its density as uniform. (b) If your fingers ...
October 24, 2011

Physics
A machine part is made from a uniform solid disk of radius R and mass M. A hole of radius R/2 is drilled into the disk, with the center of the hole at a distance R/2 from the center of the disk (the diameter of the hole spans from the center of the disk to its outer edge). ...
October 24, 2011

Physics
A ballistic pendulum consists of an arm of mass M and length L = 0.52 m. One end of the arm is pivoted so that the arm rotates freely in a vertical plane. Initially, the arm is motionless and hangs vertically from the pivot point. A projectile of the same mass M hits the lower...
October 24, 2011

Physics
A 1-kg thin hoop with a 50-cm radius rolls down a 47° slope without slipping. If the hoop starts from rest at the top of the slope, what is its translational velocity after it rolls 16 m along the slope? I got the height by 16sin47=11.7 m I tried putting the k.e and p.e ...
October 24, 2011

Physics
In a tape recorder, the magnetic tape moves at a constant linear speed of 5.6 cm/s. To maintain this constant linear speed, the angular speed of the driving spool (the take-up spool) has to change accordingly. (a) What is the angular speed of the take-up spool when it is empty...
October 21, 2011

Physics
A 21.0-g metal cylinder is placed on a turntable, with its center 90 cm from the turntable's center. The coefficient of static friction between the cylinder and the turntable's surface is ìs = 0.84. A thin, massless string of length 90 cm connects the center of ...
October 21, 2011

physics
Thanks for the help drwls. I got the correct answer, but the ratio was suppose to be 1.60/2.90.
October 21, 2011

physics
The motor of a fan turns a small wheel of radius rm = 1.60 cm.This wheel turns a belt, which is attached to a wheel of radius rf = 2.90 cmthat is mounted to the axle of the fan blades. Measured from the center of this axle, the tip of the fan blades are at a distance rb = 11.0...
October 21, 2011

Physics
A carousel at a carnival has a diameter of 6.0 m. The ride starts from rest and accelerates at a constant angular acceleration to an angular speed of 0.7 rev/s in 8.8 s. (a) What is the value of the angular acceleration? 1 0.499 rad/s^2 (b) What are the centripetal and angular...
October 21, 2011

Physics.
A monster truck has tires with a diameter of 1.10 m and is traveling at 30.0 m/s. After the brakes are applied, the truck slows uniformly and is brought to rest after the tires rotate through 49.0 turns. (a) What is the initial angular speed of the tires? (b) What is the ...
October 21, 2011

Physics
Bob I have already tried that, but that does not give correct answer.A similar problem with different values have the following: If the mass in this problem is 18 g and radius is 75 cm and mu s is 0.87 and angular velocity is 45 rpm then the tension is 0.146 N. I have no clue ...
October 20, 2011

Physics
A 21.0-g metal cylinder is placed on a turntable, with its center 90 cm from the turntable's center. The coefficient of static friction between the cylinder and the turntable's surface is ìs = 0.84. A thin, massless string of length 90 cm connects the center of ...
October 20, 2011

Physics
Two masses, m1 = 2.0 kg and m2 = 3.3 kg, are moving in the xy-plane. The velocity of their center of mass and the velocity of mass 1 relative to mass 2 are given by the vectors vcm = (−1,+2.2) m/s and vrel = (+4.5, +1.0) m/s. (a) Determine the total momentum of the ...
October 11, 2011

physics
A 1175-kg cannon shoots a 33-kg shell at an angle of 25° above the horizontal and a speed of 495 m/s. What is the recoil velocity of the cannon? (Take the direction the cannon is firing to be the positive direction. Indicate the direction with the sign of your answer.)
October 11, 2011

physics
Find the center of mass of a rectangular plate of length 10 cm and width 39 cm. The mass density varies linearly along the length. At one end, it is 8 g/cm2; at the other end, it is 18 g/cm2. (Assume the x-axis begins at the 8 g/cm2 edge and extends along the length. Assume ...
October 11, 2011

Physics
Find the location of the center of mass for a one-dimensional rod of length L and of linear density ë(x) = cx, where c is a constant. (Hint: You will need to calculate the mass in terms of c and L. Use any variable or symbol stated above as necessary.) X =
October 11, 2011

physics
A rocket consists of a payload of 4280.0 kg and 1.626 105 · of fuel. Assume that the rocket starts from rest in outer space, accelerates to its final velocity, and then begins its trip. What is the speed at which the propellant must be expelled to make the trip from the...
October 11, 2011

Physics
A jet aircraft is traveling at 180 m/s in horizontal flight. The engine takes in air at a rate of 77.0 kg/s and burns fuel at a rate of 3.15 kg/s. The exhaust gases are ejected at 595 m/s relative to the speed of the aircraft. Find the thrust of the jet engine. (Take the ...
October 11, 2011

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