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# Work

### 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.

### Density - A standard 1 kilogram weight is a cylinder 51.5 mm in height and 44.5 mm in diameter. What is the density of the material?

A standard 1 kilogram weight is a cylinder 51.5 mm in height and 44.5 mm in diameter. What is the density of the material? 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

### Dynamics: Block Attached to Spring on Incline with Friction

4. A Constant force F is applied to a body of weight W resting on an inclined surface which the coefficient of friction is The body is restrained by a spring having a spring constant of K. Compute the velocity of the body in terms of F and other parameters that are given when the body has moved from rest a distance up the inclin

### 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 &#952; = 30°. How much work is done by each of the three forces?

### find the maximum force from the force-position graph

Please see the attached document. A 650 g particle moving along the x-axis experiences the force shown in Figure Ex11.15. The particle goes from vx = 3.0 m/s at x = 0 m to vx = 4.5 m/s at x = 2 m. What is Fmax?

### Reversible Process and First Law of Thermodynamics

Show that from the definition of entropy in terms of a reversible process, that the First Law of Thermodynamics applied to a gas can be expressed in the form dU = TdS - pdV.

### Impulse and Force

During a violent thunderstorm, hail of diameter 1.0 cm falls directly downward at speed of 25m/s. There are estimated to be 120 hailstones per cubic meter of air. (a) What is the mass of each hailstone (density = 0.92 g/cm^3)? (b) Assuming that the hail does not bounce, find the magnitude of the average force on a flat roof mea

### 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 = _______.

### Pile Driver - Force, Work and Distance

A pile driver drives a pile into the ground. This means that a mass of 1000kg is lifted through 5m and released to fall freely on the pile. a) Determine the impulse produced by the pile-engine b) If it is assumed that the impulse lasts for 1/100 s, find the force on the pile. c) If 80% of the energy is effectively used in

### Particles and Waves

1.) In a television picture tube the electrons are accelerated from rest through a potential difference V. Just before an electron strikes the screen, its de Broglie wavelength is 0.8*10^-11 m. What is the potential difference? 2.) A photon has the same momentum as an electron moving with a speed of 1.6 *10^5 m/s. What is t

### 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

### Average thermal power

A 10.0 kg rock slides on a rough horizontal surface at 6.50m/s and eventually stops due to friction. The coefficient of kinetic friction between the rock and the surface is 0.300. What average thermal power is produced as the rock stops?

### 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

### Energy, Momentum and Projectile Motion

please include all diagrams and calculations and assumptions The object of a pinball game is to project the "particle" (the red ball) so that it enters the hole at E. When the spring is compressed and then released the particle is projected along the track which is smooth except for a rough patch between a and b where the c

### 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.

### Calculate the work done in compressing the spring

Please answer in detail. Thanks!! A force of 300 pounds compresses a 10-inch string to a length of 4 inches. 1) Calculate the work done in compressing the spring an additional 2 inches. 2) Calculate the work done in compressing the spring a total of 4 inches (from its natural length).

### Amount of work to accelerate

Suppose I put in 10keV (1eV = 1.6 x10-19J; 1keV = 103eV) of work to accelerate an electron (rest mass = 9.1x10-31 kg). With this amount of work, up to what speed (in terms of c) can the electron be accelerated if it starts from rest?

### Work done by the force and kinetic energy

Please see the attached. 1. A 5.0kg object is pulled along a horizontal surface at a constant speed by a 15N force acting 20 degrees above the horizontal. How much work is done by this force as the object moves 6.0 m? 2. A 4.0 kg block is lowered down a 37 degrees incline a distance of 5.0m from point A to point B. A horiz

### 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