Explore BrainMass
Share

# Work

### Work and Energy

If the work required to speed a car up from 10 km/h to 20 km/h is 5.0 x 10^3 J, what would be the work required to increase the car's speed from 20 km/h to 30 km/h?

### Mechanics: Work done against friction

The problem is: The light horizontal spring has a force constant of k=100 N/m. A 2.00 kg block is pressed against one end of the spring (compressing it 0.100 m). The block is released and moves from rest 0.250 m to the right of the release position. Show that the coefficient of kinetic friction between the block and the horizont

### Heat and work

From what height one would have to drop a block of ice so that the energy obtained would be enough to melt the block and raise the temp of the water to 50 C.

### Easy EPE Problem

An electron and a proton are initially very far apart (effectively an infinite distance apart). They are then brought together to form a hydrogen atom, in which the electron orbits the proton at an average distance of 5.41 x 10-11m. What is EPEfinal - EPEinitial, which is the change in the electric potential energy?

### The Continuity Equation

Petroleum flows along a 10-cm diameter pipeline at a speed of 2.0 m/s. Determine the flow rate, assuming the liquid is ideal.

### Work Energy and Velocity

A) Find the power input of a force F acting on a particle that moves with a velocity V for F=(6N)i - (5N)j and v = (-5 m/s)i + (4 m/s)j B) What is the angle between them?

### A Cart Pulled Up an Incline

Consider a cart being pulled up at incline at a constant velocity. a) Will the work done be different for the following two positions of the force probe: parallel to the surface of the incline and at a 45 degree angle to the surface? Explain. b) Does the starting point, mass of the cart, or angle of inclination of the surface

### A Cart on an Inclined Plane

A cart is on an inclined plane. If it is given a push up the ramp and released, then it moves up, reverses direction, and comes back down again. How will the kinetic energy change? How will the gravitational potential energy change? How will the mechanical energy change?

### The Bermuda Triangle

Please do not place your response in a .pdf or .cdx format, but Word documents are okay. Thanks! Here's the actual problem: A cylinder with initial volume V contains a sample of gas at pressure p. The gas is heated in such a way that its pressure is directly proportional to its volume. After the gas reaches the volume 3V a

### Problem 19.54

Please do not place your response in a .pdf or .cdx format, but Word documents are okay. Thanks! What is the power output of the engine? Please see attached for actual problem.

### Work at Lifting and Lowering Phase

A weight lifter is bench-pressing a barbell whose mass is 85 kg. He raises the barbell a distance of 0.65m above his chest and then lowers the barbell the same distance. The weight is raised and lowered at a constant velocity. Determine the work done by the weight lifter during (a) the lifting phase and (b) the lowering phase.

### Power Output of a Motor

The crate has a mass of 150 kg and rests on a surface for which the coefficients of static and kinetic friction are us= 0.3 and uk = 0.2 respectively. If the motor supplies a cable force of F = (8t^2 + 20) N, where t is in seconds, determine the power output developed by the motor when t= 5s.

### Kinetic Energy and Work

A 6.0 kg block is pushed 8.0 m up a rough 37 degree inclined plane by a horizontal force of 75N. If the initial speed of the block is 2.2m/s up the plane and a constant kinetic friction force of 25N opposes the motion, calculate the initial kinetic energy of the block, the work done by the 75N force, the work done by the frictio

### Basic Physics Problems (Force; Acceleration; Friction; Energy: Kinetic, Mechanical, Potential)

I would like for you to show me all of your work/calculations and the correct answer to each problem. 38. In an emergency stop to avoid an accident, a shoulder-strap seat belt holds a 60-kg passenger firmly in place. If the car were initially traveling at 90 km/h and came to a stop in 5.5 s along a straight, level road, what

### Average Power P_avg Created by Force F

A sled of mass m is being pulled horizontally by a constant upward force of magnitude F that makes an angle theta with the direction of motion. The coefficient of kinetic friction is mu_k. The average velocity of the sled is v_avg. Find the average power P_avg created by force F. Express your answer in terms of F, theta, a

### Work, Power and Force.

Please do not put your response in a .pdf format, but Word documents are okay. Thanks! (A) A sled of mass m is being pulled horizontally by a constant horizontal force of magnitude F. The coefficient of kinetic friction is mu_k. During time interval t, the sled moves a distance s, starting from rest. Find the average power Pa

### What is the total work done by the two tugboats on the supertanker?

Two tugboats pull a disabled supertanker. Each tug exerts a constant force of 1.9e10^6 N, one at an angle 12.0 degrees west of north, and the other at an angle 12.0 degrees east of north, as they pull the tanker a distance 0.700 km toward the north. What is the total work done by the two tugboats on the supertanker? Express your

### Physics Calculations: Finding the Length of a Ramp

Question: Truck brakes can fail if they get too hot. In some mountainous areas, ramps of loose gravel are constructed to stop runaway trucks that have lost their brakes. The combination of a slight upward slope and a large coefficient of friction in the gravel brings the truck safely to a halt. Suppose a gravel ramp slopes upwar

### Work done/Energy burnt using weight lifting

2.) Your new exercise machine involves lifting weights a standard height of 52.0 cm. a) How much work do you do if you lift 37.8 kg? (in J) Exercise requires a food input about four times your mechanical work output (in other words, about 25% efficiency). A "food calorie" is actually 1000 standard calories and a standard

### Mechanical Work Formulas

1. You and your roommate are dragging an exercise machine (mass 58.9 kg) down a 73.4 meter long hall, from the stair landing, where (because of union rules) the UPS driver left it, to your dorm room. The coefficient of friction with the floor is u = 0.917. a) The mechanical work you do in the process is how many kJ? b) Ass

### Block on a incline AND energy

A block of weight mg sits on an inclined plane as shown. A force of magnitude F is applied to pull the block up the incline at constant speed. The coefficient of kinetic friction between the plane and the block is Mu. What is the total work done on the block by the force of friction as the block moves a distance L up the

1. An overhead projector with a lens of 35.6-cm focal length is used to throw an image on a screen 1.80 m away. If you consider the lens to be a thin lens, how far is the slide from the lens when the image is in focus? What is the magnification in this setup? Work this problem by ray tracing? 2. Work Problem 1 using the thin-

### Coefficient of Kinetic Friction Between Football Uniforms and Astroturf After a Head-On Collision

Fred (mass 70.0 kg) is running with the football at a speed of 7.10 m/s when he is met head-on by Brutus (mass 130 kg), who is moving at 5.10 m/s. Brutus grabs Fred in a tight grip, and they fall to the ground. How far do they slide? The coefficient of kinetic friction between football uniforms and Astroturf is 0.350. Give answe

### Ups and Downs

(a) A ball is launched with initial speed v from ground level up a frictionless slope. The slope makes an angle theta with the horizontal. Using conservation of energy, find the maximum vertical height hmax to which the ball will climb. Express your answer in terms of v, g, and theta. You may or may not use all of these quantiti

### Example Physics Problems

1. If there is a maximum frictional force between your shoe and the track, does that set a limit on how fast your can start (accelerate) in sprint? Does that mean you cannot have more than a certain acceleration even if your have increduly strong leg muscles? What is done to solve this problem? 2. Explain why friction is impo

### Basic Physics (Tension; Displacement; Force etc.)

A 230kg crate hangs from the end of a rope of length L-12.0m. You push horizontally on the crate with a varying force F to move it distance d=4.00m to the side (see attached picture). (a) what is the magnitude of F when the crate is in this final position? During the crate's displacement, what are (b) the total work done on i

### Kinetics Problems

A skier is pulled by a tow rope up a frictionless ski slope that makes an angel of 12 degree with the horizontal. The rope moves parallel to the slope with a constant speed of 1.0m/s. The force of the rope does 900J of work on the skier as the skier moves a distance of 8.0m up the incline. (a) If the rope moved with a constant s

### Roller Coaster Physics

ROLLER COASTER DESIGN Designing a roler coaster is very tricky. Patrons of theme and amusement parks want to be thrilled , but generally do not want to be injured. Downard accelerations of greater than 10 g cause bodily harm. Negative (i.e upward) accelerations of greater than about 5 g also cause damage ( "red out") The

### Distance Calculations of a Football Field

80. To go to a football stadium from your house, you first drive 1000 m north, then 500 m west, and finally 1500 m south. (a) Relative to your home, the football stadium is (1) north of west, (2) south of east, (3) north of east, or (4) south of west. (b) What is the straight-line distance from your house to the stadium? 8

### Roller Coaster Work Problem

The questions refer to the roller coaster in the diagram (attached). The mass of the roller coaster, including passengers = 500 kg. Assume that friction and drag forces are so small they can be ignored. 1. Measured from "ground level," what is the gravitational potential energy of the roller coaster at the top of the first hi