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3 good questions in mechanics: Force, work and energy.

Please see the attached file for full problem description. 1.) To immobilize a fractured femur, doctors often utilize the Russell traction system illustrated in the figure below. Notice that one force is applied directly to the knee, F1, while two other forces, F2 and F3, are applied to the foot. The latter two forces combine

Simple Machines: Force required to push a box up a ramp.

1. A 400-lb piano on frictionless casters is to be pushed up a 20 ft ramp to a loading platform 3 ft above the ground. How much force is needed? 2. A block weighing 250 lbs is to be raised into a wagon 30 in high by a boy who can only exert a force of 50 lbs. (a) what is the shortest board he must use as an inclined plane wh

Projectile motion

In a local bar, a customer slides an empty beer mug down the counter for a refill. The bartender is momentarily distracted and does not see the mug, which slides off the counter and strikes the floor at distance d from the base of the counter. The height of the counter is h. (a) With what speed did the mug leave the counter?

Density of a Proton: Nucleus of a Hydrogren Atom

A proton, which is the nucleus of a hydrogen atom, can be modeled as a sphere with a diameter of 2.4 fm and a mass of 1.67 10^(-27) kg. Determine the density of the proton in kg/m^3 and show all work.

Work, energy and momentum

5) Two bumper cars collide head-on. Before the collision, car 1 is coming from the right at 3 m/s and has a total mass of 200 kg. Car 2 is coming from the left at 5 m/s and has a total mass of 250 kg (the driver of car 2 is a lot fatter than the driver of car 1) At the time of the collision, the bumpers lock and the cars rem

Work Problem - Physics

The length a spring si stretched from its natural lenght with work, W foot pounds, given by L + square root(2W/K) where k is constant for the given spring. If a spring has constant 76.4 and the spring is to be stretched 3.6 feet from its natural length, how much work will be necessary? 72.5? 137.5? 495.1? or 990.1? foot pounds

work done by force when dragging a crate

Please see the attached file for full description and figure The two ropes shown in the bird's-eye view of Figure Ex11.10 are used to drag a crate 3.5 m across the floor, with fk =505N, T1 = 326.00 N and θ = 30°. How much work is done by each of the three forces?

Photoelectric Effect: Energy of Photoelectrons Emitted

Light from a laser hits the surface of cesium. With a minimum photon energy of 2.14eV being required to remove photons. When the surface of cesium is illuminated with this light photoelectrons are emitted with a max kinetic energy of 0.76eV. Assuming that the Planck constant is 4.14x10^-15 eV Hz-1. What would be the energy of

Work & Power

Work & Power - Involves you walking up a flight of stairs and recording your time via a stopwatch or chronograph.You will be asked to make measurements and calculations for the total time to walk the flight of stairs (at least 7 steps) and the vertical height of the stairs from the bottom to the top. o Estimate your mass in kg

Atwood's Machine

In a simulation, m1 is 1.0 kg and m2 is 1.1 kg. Mass m2 rests on the floor that exerts a normal force, FN, on m2. There is no motion (i.e.. the system is in equilibrium). What is the normal force, FN, and what is the tension, T, in the rope? T (at t = 2.54 s) = ______. At equilibrium: FN + T - m2 ? g = 0. Then FN = _______.

Energy and work

Please see attachment. 12. A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance. 13. A helicopter is cruising at a speed of 25.0 m/s at an altitude of 185 m. What is the total mechanical energy of

uniform ball and silver dollar rolling down a curved track

In a lab experiment you let a uniform ball roll down a curved track. The ball starts from rest and rolls without slipping. While on the track, the ball descends a vertical distance h. The lower end of the track is horizontal and extends over the edge of the lab table; the ball leaves the track traveling horizontally. While free

Swing - Potential energy, speed etc.

A 23.0 kg child plays on a swing having support ropes that are 1.90 m long. A friend pulls her back until the ropes are 39.0 (degrees) from the vertical and releases her from rest. Part a: What is the potential energy for the child just as she is released, compared with the potential energy at the bottom of the swing? V=

Work done by earth on moon and by sun on earth.

Assume that the earth and the moon have circular orbits (which is almost true) and that the periods of their orbits are 365 days and 28.0 days, respectively How much work does the earth do on the moon in one day? W(earth)= ? J How much work does the sun do on the earth in one month? W(sun)= ?J

Work done on a cutting tool.

A cutting tool under microprocessor control has several forces acting on it. One force is F = -alpha xy^{2} hat{ j }, a force in the negative y-direction whose magnitude depends on the position of the tool. The constant is alpha = 2.25 N/m^3. Consider the displacement of the tool from the origin to the point x = 2.10 m, y = 2.

Electrostatics: Electric Potential Energy

How much work in Joules would it take to push two protons very slowly from a separation of 2.00 * 10^- 10m (a typical atomic distance) to 3.00 * 10^-15}m (a typical nuclear distance)? If the protons are both released from rest at the closer distance in part A, how fast are they moving when they reach their original separation

conservative force and the corresponding potential energy

Which of the following forces is conservative? (a)F=k(x,2y,3z) where k is a constant. (b)F=k(y,x,0)(c)F=k(-y,x,0). For those which are conservative, find the corresponding potential energy U, and verify by direct differentiation that F=-gadU.

angular velocity of the particle and work done

A particle of mass m is moving on a frictionless horizontal table and is attached to a massless string, whose other end passes through a hole in the table, where I'm holding it. Initially, the particle is moving in a circle of radius r0 with angular velocity w0, but I now pull the string down through the whole until at length r

electron and the infinite charged plane

An electron is released from rest 2.0 cm from an infinite charged plane. It accelerates toward the plane and collides with a speed of 1.0 x 10^7 m/s A) What is the surface charge density of the plane in C/m^2? B) What is the time required for the electron to travel the 2.0 cm?

Heat Engine Operating Between A Water Tank and A River

A heat engine operates between a tank containing 1*10^3 m^3 of water and a river at a constant temperature of 10 degrees Celsius. If the temperature of the tank is initially 100 degrees Celsius, what is the maximum amount of work that the heat engine can perform?

work done by each force on a box being pushed

A 48 kg box is being pushed a distance of 7.0 m across the floor by a force P whose magnitude is 143 N. The force P is parallel to the displacement of the box. The coefficient of kinetic friction is 0.25. Determine the work done on the box by each of the four forces that act on the box. Be sure to include the proper plus or minu

change in electric potential energy

1. A uniform electric field with a magnitude of 6050 N/C points in the positive x direction. Find the change in electric potential energy with a +12.5-µC charge is moved 5.50 cm in (a) the positive x direction (b) the negative x direction, and (c) in the positive y direction. 2. Points A and B have electric potentials of

How do lasers work?

Describe how a thorough understanding of the energy levels in atoms was necessary before lasers could be developed.

how far does the box slide before it stops

Box slides with v=4.5m/s down a horizontal surface. At point P, it encounters a rough section. The coefficient of friction is not constant. It begins at .100 at P and increases linearly to .600 at a distance of 12.5m away from P. A) Using work-energy theorem, how far does the box slide before it stops? B) What is the coef

Determine how far the skier will slide before coming to rest

A skier on a slope inclined at 4.7 degrees to the horizontal pushes on ski poles and starts down the slope. The initial speed is 2.7m/s. The coefficient of kinetic friction between skis and snow is .11. Determine how far the skier will slide before coming to rest.

Calculate the tension of the string in Newtons.

The goal is to give a guitar maker a list of the separation between successive frets on the neck of the guitar. In the figure attached, the frets are the thin metal bars transverse to the neck of the instrument. When a string is pressed against a fret with a finger, its effective length is the distance from the fret to the bridg