Frictional force Definition and 260 Threads

Homework Statement A 20-kg block on a horizontal surface is attached to a light spring (force constant = 8.0 kN/m). The block is pulled 10 cm to the right from its equilibrium position and released from rest. When the block has moved 2.0 cm toward its equilibrium position, its kinetic energy...

A block is projected up an incline making an angle theta with the horizontal. It returns to its initial position with half its initial speed. I have absolutely no idea how to do this problem. I would think i would have to use the equation x = x +v(t) + (1/2)at^2 or maybe the equation x=...

Homework Statement You see the boy next door trying to push a crate down the sidewalk. He can barely keep it moving, and his feet occasionally slip. You start to wonder how heavy the crate is. You call to ask the boy his mass, and he replies " 45.0 kg." From your recent physics class you...

Instead of answering all the questions being asked bfeore i make the topic, I'm just going to show you a scan of what I'm being asked for: http://img184.imageshack.us/img184/7313/picture123146ut0.png Basically, I got down the normal force, and Idk if made a mistake when i tried to find...

Homework Statement A car (m = 1710 kg) is parked on a road that rises 14.7 ° above the horizontal. What are the magnitudes of (a) the normal force and (b) the static frictional force that the ground exerts on the tires? Coefficient of static friction: rubber on dry concrete: 1.0...

Homework Statement Answer Chapter 6, Problem 73 Cutnell & Johnson 7th edition A 356 N force is pulling an 90.2-kg refrigerator across a horizontal surface. The force acts at an angle of 25.6 ° above the surface. The coefficient of kinetic friction is 0.258, and the refrigerator moves...

[SOLVED] Frictional Force Block Problem---VERY EASY But need HELP! Homework Statement

Homework Statement http://docs.google.com/TeamPresent?docid=dm9wjvk_10fk863j&skipauth=true In the above file, a force at the top of the wheel is acting towards, right, and the friction at the bottom towards left. But shouldn't the frictional force at the bottom point towards right? Homework...

Homework Statement With what frictional force must the road push on a 1200 kg car if the driver exceeds the speed for which the curve was designed by deltav = 14km/hr? The Attempt at a Solution I actually have no clue where to begin with this question. Don't I need the radius to figure...

Homework Statement A brick is on a 121 cm plank, and the plank is lifted gradually until the brick begins to slide, when the plank is lifted 48cm in the air at an angle of 30º. I need to find the Frictional Force, and µ kinetic. How do I find these things knowing only these three things...

Homework Statement A car is driven around a track of radius R=100m which is banked at 30degrees to the horizontal. If the coefficients of static friction between the wheels and the road is Us=0.8, find the maximum speed for the car to stay on the road without skidding sideways. Homework...

Homework Statement An easy question, but I'm not getting it: A 3.5kg block is pushed along a horizontal floor by a force F of mag 15N at an angle of 40 deg with teh horizontal. The coefficiennt of kinetic firction b/t the block and the floor is 0.25. Find the frictional force on the block...

Homework Statement The 1.6kg, 20cm diameter disk in the figure below is spinning at 240rpm. How much friction force must the brake apply to the rim to bring the disk to a halt in 3.5s? http://i241.photobucket.com/albums/ff4/alg5045/p13-69.gif Homework Equations The Attempt at a...

a block is at rest on the incline shown in the figure. the coefficients of static and kinetic friction are s = 0.42 and k = 0.36 respectively. The acceleration of gravity is 9.8 m/s^2. the angle of inclination is 19 degrees. what is the frictional force acting on the 43 kg mass? answer in...

Direction of frictional force! Help! Homework Statement What is the direction of the frictional force for each question? OR is there not enough info given to answer the question? 1) http://www.learning.physics.dal.ca/library/Graphics/Gtype10/block01-19.gif 2)...

Homework Statement Part A: A box of mass m is sliding along a horizontal surface. The box leaves position x = 0 with speed v_0. The box is slowed by a constant frictional force until it comes to rest at position x = x_1. Find F_f, the magnitude of the average frictional force that...

Homework Statement Q : A train of mass 8.0 \times 10^{}6 kg, traveling at a speed of 30 m s^{}-1, brakes and comes to rest with a constant deceleration in 25s. (a) Calculate the frictional force acting on the train while decelerating. (b) Calculate the stopping distance of the train...

1. The problem: 2 blocks are arranged at the ends of a massless string (mass one is on a table and mass two is hanging straight down off the other side of the pulley that is connected to the edge of the table). The system starts from rest. When the 4.18 kg (the hanging mass) mass has fallen...

Homework Statement A block is at rest on the incline (32 degrees from the horizontal). The coefficients of static and kinetic friction are Us=0.73 and Uk=0.62 respectively. The acceleration of gravity is 9.8 m/s^2. What is the frictional force acting on the 39 kg mass? PART 2: What is...

Suppose that an object is moving up an inclined plane, then stops and after moves down. There exists frictional force. How do you represent the frictional force when v=0, when it stops? Or it has a zero value? Thanks.

Hey all, i'm doing a physics research on snooker but i don't really know the approximate frictional force acting between the pool table surface (which is made of a wool called baize) and the cue ball. Does anyone know it cos i need to calculate the decceleration of the cue ball as it rolls...

Frictional Fore m=0.2kg h1=1.65m h2=0m v1=0m/s v2=4.02m/s http://img339.imageshack.us/img339/7201/11ei1.png Calculate the frictinal Force

INTRODUCTION: This is a problem from my Introduction to Physical Science class using "Conceptual Physics" 10th Ed.by Paul G. Hewitt EXACT PROBLEM: "A hockey puck slides 20.0m across a frozen pond in a time of 8.0 seconds before coming to a rest." PROBLEMS FACED: Find the coefficient of...

INTRODUCTION: This is a problem from my Introduction to Physical Science class using "Conceptual Physics" 10th Ed.by Paul G. Hewitt EXACT PROBLEM: "A 15-N cart rests in the isle of a jet airplane that is cruising horizontally at a constant velocity. The coefficient of static friction between...

A 20kg sled has final velocity of 20m/s after it ascended a 25m tall hill. I calculated the initial velocity as 30m/s: v_0 = \sqrt{{20\frac{m}{s^2}^2}+2\times10\frac{m}{s^2}\times25m v_0 = 30\frac{m}{s} Now, if 1500J of work is being done by friction, how can I find the final velocity...

Hello there! This problem is giving me a hard time and I thought maybe one of you could give me a hint: "A ship is going upstream with a constant power P. Its speed V is relative to the water and the water's speed U is relative to the shore. The ship needs tp overcome a frictional force...

Hi, I 'm just reviewing some forces problem. I have this one question that I was wondering if anyone could please clarify for me. Thank you. Question: Block B is initially at rest on block A, which is at rest on a smooth frictionless floor. There is friction between block A and block B...

I really am not getting this physics stuff...again I thought I had this one figured out but it doesn't seem to be right. So the question... A 49.2 kg car is moving at 12.6 m/s around a horizontal curve whose radius is 31.3 m. What is the magnitude of the fictional force required to keep the...

Hey there, I need a nudge in the right direction on two problems. Can you anyone help me out. I will post the other question seperately in a few :) Here we go: 1) A bead is sliding along a stiff wire track. The bead is released from rest at point A and comes to a stop (momentarily)...

I'm doing revision work from the beginning of the year and I can't find the formulas for these two questions. - 1) Calculate the velocity of the pellet before it strikes the putty 2) Calculate the average frictional force it takes for the car to come to rest if its traveling at 15ms and...

Question: A force of 29.0 N is applied to a 3.00kg block which is initially at rest on a rough horizontal surface. A 2.00kg block is initially at rest on the 3.00kg block. The coefficient of friction between the blocks is \mu_s=0.35 and the kinetic friction between the 3.00kg block and the...

The first problem says that a 68 kg crate is dragged across a floor by pulling a rope at a 15 degree angle to the ground. 1. If the static friction coefficient is 0.5, what is the minimum tension needed to start the crate's motion? I did Tcos15 = 0.5(mg) and got 344.95, but my book says...

i got most of this problem but i don't know what average frictional force means. A 25 kg bear slides, from rest, 13 m down a lodgepole pine tree, moving with a speed of 6.4 m/s just before hitting the ground. (a) What change occurs in the gravitational potential energy of the bear-Earth...

Hi there, I'm doing a problem in my book ("Check your understanding" 4.3 in Cutnell/Johnson, 7th ed.). The book says the answer is x=43 degrees, but I don't know how to find it exactly. Given that it's an in-chapter problem, I'm guessing there's something wrong with my brain, but I'd...

An 18.8kg box is released on a 38.0o incline and accelerates down the incline at 0.281m/s2. What is the magnitude of the friction force impeding its motion. F = m*g*cos(38) sum forces parallel to the plane m*g*sin(38) - (mu)*(F) = m*a, or m*g*sin(38) - (mu)*m*g*cos(38) = m*a masses cancel...

A cup of coffee is sitting on a table in an airplane that is flying at a constant altitude and a constant velocity. The coefficient of static friction between the cup and the table is 0.30. Suddenly, the plane accelerates, its altitude remaining constant. What is the maximum acceleration that...

Ok, I need to find the frictional force on sphere of radius a and mass M moving with velocity v in an ideal gas at temperature T. If I put myself in the sphere frame, then diffrential cross-section is \frac{d\sigma}{d\Omega} = \frac{a^2}{4} and the total cross-section is...

A skydiver jumps from an airplane and descends at a constant velocity of 2m/s. The mass of the skydiver and his equipment is 70kg. Calculate the magnitude of the air's frictional force acting on the skydiver and his equipment. F = 70kg x 9,8N/kg = 686N I'm lost

A 17 kg block is at rest on an incline with angle 33. The coefficients of static and kinetic friction are 0.7 and0 0.59, respectively. The acceleration of gravity is 9.8m/s^2. 1) What is the frictional force actin on the 17kg mass? 2) What is the larges angle the incline can have so...

A 3.80-kg box is sliding across the horizontal floor of an elevator. The coefficient of kinetic friction between the box and the floor is 0.500. Determine the kinetic frictional force that acts on the box when the elevator is (a) accelerating upward with an acceleration whose magnitude is...

Okay, I have tried this problem 13 times, used up 13 sheets of paper and I just don't know how to do this. Do ask me what I don't know, because I just don't understand physics, and no one I have asked can explain it to me in a way that I can understand it. Please I hope someone can expain how...

Im reading a wonderful book called Springer Handbook of Nano-technology and I am on the chapter dealing with how the AFM (atomic force microscope) works. Upon the section describing how it works with frictional forces I ran into a bit of a complex. If we're imaging the topography of some...

I've been working on this problem for hours and I just can't figure out what to do next! Here it is- A car drives around a curve with radius 410 m at a speed of 32 m/s. The road is banked at 5.0 degrees. The mass of the car is 1400 kg. What is the frictional force on the car? I drew...

I'm working on the physics behind a Scene in Spiderman, where the Green Goblin is standing on top of a bridge, holding a cable. along that cable is a cable car full of screaming little kids. I calculated the force pulling on the Goblin to be about 23,000lbs...and I'm sure even with his 800%...

A stationary car of weight W on a road sloping at 30 degrees to the horizontal. The frictional force on the car is 4000 N acting up the road BC. http://img156.exs.cx/img156/5915/phy6dj.png What is (a) the weight W (b) the normal contact force R of the road surface on the car?

I am really stuck on how to even start solving this problem, can someone help me please! A 2.5 kg block is pushed along a horizontal floor by a force F of magnitude 17 N at an angle = 35° with the horizontal. The coefficient of kinetic friction between the block and floor is 0.25...

Frictional Force, PLEASE HELP! A rifle with a barrel length of 55.0cm fires a 12.0g bullet with a horizontal speed of 350m/s. The bullet strikes a block of wood and penetrates to a depth of 11.0cm. What frictional force (assumed to be constant) does the wood exert on the bullet? heres what i...

A 300N force is pulling an 90.0 kg refrigerator across a horizontal surface. The force acts at an angle of 22.0° above the surface. The coefficient of kinetic friction is 0.200, and the refrigerator moves a distance of 6.00 m. i found out the work done by pulling force is 1669 J and its...

lol... sorry for posting again but now I am confused about frictional force on my roller coaster... When an object reaches the top of the loop of a roller coaster, what direction is it traveling in? Friction force will be opposite of that direction... At the exact top of the roller coaster...

What is frictional force and its causes to increase or decrease?