Explore BrainMass

# Work

## BrainMass Solutions Available for Instant Download

### A pitcher throws a baseball with mass=.145kg straight up with initial v=25 m/s

A pitcher throws a baseball with mass=.145kg straight up with initial v=25 m/s a) How much work has gravity done on the ball when it reaches h=20m above pitcher's hand? b) Using work-energy theorem, calculate speed of baseball at h=20m above pitcher's hand c) Does the answer to part b depend on weather the ball is moving up

### Final Temperature of an Insulated Tank

An insulated tank is divided into two parts by a partition. One part of the tank contains 2.5 kg of compressed liquid water at 60 degrees C and 600 kPa while the other part is evacuated. The partition is now removed, and the water expands to fill the entire tank. Determine the final temperature of the water and the volume of

### Potential energy

A shot-putter puts a shot (weight=0.71 N) that leaves his hand at a distance of 1.52 m above the ground. a.) What is the work done by the gravitational force when the shot has risen to a height of 2.13 m above the ground. d.) What is the change in the gravitational potential energy of the shot.

### work done by gravitational force and potential energy

A 0.60 kg ball is dropped out of a window that is 6.1 m above the ground. The ball is caught by a person whose hands are 1.5 m above the ground. a.) How much work is done on the ball by its weight? What is the gravitational potential energy of the basketball, relative to the ground, when it is b.)released and c) caught

### Work Done by Forces and Work-Energy Theorem

A rescue helicopter lifts a 79 kg person straight up by means of a cable. The person has an upward acceleration of 0.70 m/s^2 and is lifted from rest through a distance of 11 m. a) What is the tension in the cable? How much work is done by b) the tension in the cable and c) the person's weight d) using the work and energy theore

### Modern Physics - What is the work done on the jet by the catapult?

A fighter jet is launched from an aircraft carrier with the aid of its own engines and a steam-powered catapult. The thrust of its engines is 2.3 x 10^5 N. In being launched from rest it moves through a distance of 87 m and has a kinetic energy of 4.5 x 10^7 J at lift-off. What is the work done on the jet by the catapult?

### Modern Physics - magnitude of pushing force P

A 1.00 x 10^2 kg crate is being pushed across a horizontal floor by a force P that makes an angle of 30.0 degrees below the horizontal. The coefficient of kinetic friction is .200. What should be the magnitude of P, sot that the net work done by it and the kinetic frictional force is zero?

### Work Done by the Escalator and the Gravitational Force

A 75.0 kg man is riding an escalator in a shopping mall. The escalator moves the man at a constant velocity from ground level to the floor above, a vertical height of 4.60 m. What is the work done on the man by a) the gravitational force and b) the escalator?

### Barrel on inclined plane

A 40 kilogram barrel is rolled up a 10 meter ramp to a hieght of 5 meters. A) How much does the barrel weight? b) How much work was done? c) If the person exerted an effort force of 250 newtons to roll the barrel along the ramp, what is the efficiency of the ramp?

### kinetic energy and distance penetrated by the pile

A pile is driven into the ground by a hammer of mass (M) 500Kg, dropped from a height of 4 meters. The mass (m) of the pile is 40Kg and the average resistance of the ground to penetration (Fr) is 45 kN. 1) Calculate the Velocity and the kinetic energy of the hammer prior to the impact with the pile. 2) Calculate the velo

### An arrow, starting from rest, leaves the bow with a speed of 25.0 m/s. If the average force exreted on the arrow by the bow were doubled, all else remaining the same, with what speed would the arrow leave the bow?

An arrow, starting from rest, leaves the bow with a speed of 25.0 m/s. If the average force exreted on the arrow by the bow were doubled, all else remaining the same, with what speed would the arrow leave the bow?

### Three circular motion questions

A couple of circular motion problems... I realize that this is something I could have figured out if I had more time, but I am running out of it..please help. 1. A circular disk of radius 30 cm is rotating with an angular acceleration of 1 radian/ s2. What is the tangential acceleration of a point on the rim of the disk? Wha

### In moving out of a dormitory at the end of the semester

In moving out of a dormitory at the end of the semester, a student does 1.6 x 10^4 J of work. In the process, his internal energy decreases by 4.2 x 10^4 J. Determine each of the following quantities (including the algebraic sign): (a)W, (b) delta U, and (c)Q.

### Work, Energy, and Friction

Two blocks, A and B (with mass 50 kg and 100 kg, respectively), are connected by a string, as shown in Figure. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between block A and the incline is µk = 0.29. Determine the change in the kinetic energy of block A as it moves from C to D, a dist

### Varying coefficient of friction

A box is sliding with a speed of 4.50 m/s on a horizontal surface, when at point P, it encounters a rough section. On the rough section, the coefficient of friction is not constant, but starts at 0.100 at P and increases linearly with distance past P, reaching a value of 0.600 at 12.5 m past point P. a) use the work-energy

### Block sliding down an inclined plane

A block slides down an incline (see the fig. in the attachment). As it moves from point A to point B, which are 6.6 m apart force F acts on the block, with magnitude 3.3 N and directed down the incline. The magnitude of the frictional force acting on the block is 6.1 N. If the kinetic energy of the block increases by 28 J bet

### Rotational mechanics, hydrostatics and hydrodynamics.

1 The arm in Figure P8.7 weighs 36.0 N. The force of gravity acting on the arm acts through point A. Determine the magnitudes of the tension force t in the deltoid muscle and the force s of the shoulder on the humerus (upper-arm bone) to hold the arm in the position shown. 2. One end of a uniform 6.0 m long rod of weigh

### Multiple choice questions related to wave mechanics, fluid dynamics, simple harmonic motion, gravitational filed, angular momentum and center of mass.

(See attached file for full problem description) --- An 82.0 kg-diver stands at the edge of a light 5.00-m diving board, which is supported by two pillars 1.60 m apart. Find the force exerted by pillar B: a. 1.71 kN downwards. b. 1.71 kN upwards. c. 2.51 kN downwards. d. 2.51 kN upwards. A meter stick balan

### Working with Energy Unit Conversion

An insulated system takes in 6.50 kcal of heat and has 2000 J of work done on it. What is the change in internal energy if the system? I believe the answer is 29.2 kJ. I need to see each step and formula to solve this question. Please assume I know nothing because this would be the correct assumption.

### heat absorbed by water and work done on lifting

(a) How many joules are required to raise 1.0 kg of water from room temperature of 22^oC to its boiling point? (b) If this work were used to lift a 50-kg boy instead, how high could he be lifted? I need to see each step and formula to solve this question.

### Friction Problems

See attached file for full problem description. --- 1. a) A block with a mass m is pulled along a horizontal surface for a distance +x by a constant force F at an angle theta with respect to the horizontal. The coefficient of kinetic friction between block and table is µ. Is the force exerted by friction equal to µmg?

### Physics/ answers to questions

1. Which one of the following statements best explains why it is possible to define an electrostatic potential in a region of space that contains an electrostatic field? a. Work must be done to bring two positive charges closer together b. Like charges repel one another and unlike charges attract one another c. A positive c

### Work-Energy Concepts

A 5.0g bullet if fired horizontally into a 2.0kg wooden block resting on a horizontal surface. The coefficient of kinetic friction between block and surface is 0.20. The bullet remains imbedded in the block, which slides 0.105m along the surface. What was the initial speed of the bullet? (My problem with this is that there is no

### Work, Energy, Friction

A car is travelling on a level road with speed v1 at the instant when the brakes are applied. Assume that the wheels are locked and the car is skidding, so the friction force between the tires and the road is kinetic friction with coefficient mu_k. a) Use the work-energy relation to calculate the minimum stopping distance of

### Work-Energy Concepts

A little red wagon with a mass of 4.60 kg moves in a straight line on a frictionless horizontal surface. It has an initial speed of 10.0m/s and then is pulled 4.0 m by a force with a magnitude of 18.0 N in the direction of the initial velocity. a) Use the work-energy relation to calculate the wagon's final speed. b) Calculate

### Energy Concepts for Combined Mass

You and your bicycle have a combined mass of 95 kg. When you reach the base of an overpass, you are travelling along the road at 3.0 m/s. If the vertical height of the overpass is 5.20 m and your speed at the top is 1.5 m/s, how much work have you done in getting to the top? (Ignore friction and any inefficiency in the bike or y

### Identical Charged Particles: Potential Energy & Particle Speed

Consider three identical charged particles with charge +Q and mass m. They are held in place at the vertices of an equilateral triangle of side 1. (a) What is the potential energy of the system? (b) If they are released from rest, find the speed of each particle when they are far away from each other.

### How much work is done on a block after the force is applied?

A constant horizontal force of 2.29 N is applied to a 1.82-kg block initially at rest on a friction-free surface. How much work is done on the block in the first 1.35 seconds after the force is applied?

### Frictional Retarding Force

A worker does 300 J of work against a frictional retarding force of 15 N in pushing a power sweeper across a floor in 3.0 Seconds. If the sweeper moves with a constant speed, how fast is it going? I believe the answer is 6.7 m/s. I need to see each step and formula to solve this question.

### Forces in parallel

2 forces parallel to the X axis do 14.7 Joules of work on a small tray while moving it 20.7 meters in the X direction across a gym floor. One of the forces has a value of +3.89 Newton's in the X direction. What is the other force?