Newtons law Definition and 97 Threads

Homework Statement Two crates, of mass 75 kg and 110 kg are in contact and at rest on a horizontal surface. A 620N force is exerted on the 75 kg crate. If the coefficient of kinetic friction is 0.15 calculate: a) the acceleration of the system b)the force that each crate exerts on the...

Homework Statement your car rolls on a level street at 50km/h. the coefficient of kinetic friction is 0.023. how far will the car go before stopping. (no breaking.) Homework Equations The Attempt at a Solution F_fric=0.226m F_a=(-1250/s)*m i need to make F_a-F_fric equal to...

Why do we choose to use the work energy principle instead of the Newtons law to analyze the motion of a system of rigid bodies?

Homework Statement A hot - air balloon experiences an acceleration of 1.10 m/s^2 [down]. The total mass of the balloon, the basket, and the contents of the basket is 315 kg. The balloonist wishes to change the acceleration to zero. There is no fuel left to heat the air in the balloon...

Homework Statement * This is for my project. The sled is placed at an inclined surface at an angle of theta. The sled is attatched to a rope, which i will be pulling to find out the minimum force to start the sled moving. i would assume that when I am tryin to find the jusssttt jussst...

I posted a post in precalculus section because i needed help solving an equation, but I'm stuck on finding tension. Could someone point me in the right direction on how to find tension for this problem? https://www.physicsforums.com/showthread.php?t=358699

Question reads: An exceptional vertical jump from rest would raise a person 0.80m off the ground. to do this what constant force would a 70.0 kg person have to exert againts the ground. Assume the person lowers himself by 0.20m prior to jumping and remains in a standing position while in the...

Question reads: A rocket of mass 1000 kg is being fired to a height of 5000m. The rocket engine shuts off when the rocket reaches a height of 1000m, and the rocket coasts up to 5000m. a) what velocity must the rocket have at the 1000m point to enable it to reach 5000m ? b) what acceleraation...

A gust of wind blows an apple from a tree. As the apple falls, the force of gravity on the apple is 9.36 N downward, and the force of the wind on the apple is 1.99 N to the right. ///////What is the magnitude of the net external force on the apple? Answer in units of N. ///////What is the...

A projectile has been launched and moves according to the equations: y = 6.00 + 3.45t − 7.20t2 m, and x = 17.0t m. (a) Do these equations describe an object launched on Earth? (b) Assume the object is a slide rule of mass 0.207 kg. What force is being exerted on it? I know part a is no...

Homework Statement On vacation, your 1300 kg car pulls a 540 kg trailer away from a stop light with an acceleration of 2.00 m/s2. (a) What is the net force exerted by the car on the trailer? (b) What force does the trailer exert on the car? (c) What is the net force acting on the car...

Homework Statement Which of the following statements about Newton’s Universal Law of Gravity is false? A. The heavier mass exerts a force on the lighter mass that is equal but opposite to the force the lighter mass exerts on the heavier mass. B. A heavy mass from far away can exert the...

Two forces, of magnitude 10N and 4N, are applied to an object. The relative direction of the forces is unknown. The net force acting on the object __________. Check all that apply ? a) cannot be equal to 5N b)cannot be equal to 10N c)cannot be directed the same way as the force of 10N...

Hello Maybe I am standing on a garden hose (great German adage, does it exist in english or are you confused what I am talking about?) Okay, to the topic: Just for one dimension. It is easier: We have m\ddot{x} = F(x(t)) Now my book tells me that if I expansion with the velocity I should...

here is my 4 problems. attached is my attempt at #2...any input would be great.

Homework Statement A hockey puck of mass m is attached to a string that passes through a hole in the center of a table. The Hockey Puck moves in a circle or radius r. Tied to the other end of the string, and hanging vertically beneath the table is Mass M.. Assuming the table top is perfectly...

Have a difficult time on where to start here, iv'e looked over the book, and my notes, and I believe the question is more basic than given, Am I thinking too in depth here? Help please! A 0.110 kg baseball, traveling 34.0 m/s, strikes the catcher's mitt, which recoils 14.0 cm in...

Homework Statement Tell me what is wrong with this question- A donkey which has heard of Newtons third law but not understood it very well refuses to pull a cart attached to it because it argues that: ' If i pull on the cart with a certain force, Newton's third law would imply an equal but...

this is going to sound dumb, but here i go. through out my schooling i was preached " in a vaccum, a feather and a bowling ball would fall at the same rate". -thinking about the difference in theories with Aristotol, Galileo, and Newton, something didn't make sense to me. Talking about...

Homework Statement Imagine taking your dog for a walk. You feel a real bond for man's best friend. Could this be due to gravitational attraction? Estimate the force of gravity between you and your dog. Homework Equations force~mass1 x mass2 divided by distance^2 The Attempt at a...

Homework Statement Check out my attachment to get an idea what is happening. What we have is an inclined plane with 2 masses (m1 and m2) which are touching one another and the angle of the incline is 30 degrees. The coefficient of kinetic friction between m1 and the plane is 0.23 = mu_k1...

Hi guys. This is my first post. I am currently on an engineering apprenticeship and its mostly practical but i have been given a Newtons law question which i am finding very hard. I have attempted it but still come up stuck. I have attached the question with the drawing. I have...

Homework Statement What is the ratio of the gravitationalpull of the sun on the moon to that of the Earth on the moon?(Assume the distance of the moon from the suncan be approximated by the distance of the Earth from the sun.) Homework Equations F_{g} =...

Newtons law, interacting objects question?? A block of mass 5.00 Kg sits on top of a second block of mass 15.0 Kg, which in turn sits on a horizontal table. The coefficients of friction between the two blocks are : μs = 0.300 and μk = 0.100. The coefficients of friction between the lower...

can someone please help to reason out this. because i am confused...is the question about static friction..please help On a truck which is moving straightforward on an horizontal road there is a big cube of concrete of mass m. The mass of the truck is M. The truck brakes suddenly with an...

Homework Statement three blocks attatched by cords that loop over frictionless pulleys. Block B lies on frictionless table, block a hangs off the left side of the table, while block c hangs off the right side. mass a= 6kg mass b= 8kg and mass c= 10kg. When the blocks are released, what is the...

Homework Statement The equation dQ/dt = k ( T - Troom) is Newtons law of cooling. dQ/dT being the rate of heat loss. I want to convert this equation to dT/dt, the rate of temperature decay. How do i go about doing this? Homework Equations The Attempt at a Solution Is Q...

I'm reading section 17 of Mathematical Physics by Donald H. Menzel on Harmonic functions. They start with Newtons law of gravitation (although the following method can be aplied to any potential field with a 1/r dependence.) see...

Homework Statement You are dragging a stack of shoeboxes along the floor by a rope (an odd situation I must say). If the total mass of the shoeboxes is 18kg and the rope is pulled at an angle of 45 degrees with no acceleration i) what is N (normal force)? and ii) What is the tension of...

a 20 kg box is on frictionless surface acted on by two horizontal surfaces. when in same direction, it pulls 11 m/s but in opposite directions, it pulls only 1 m/s. determine magnitude of each force. answer: 120 N , 100 N okay...i need help with this. i am using Newtons law: force=mass x...

Homework Statement A uniform chain of length L, measured in feet, is held vertically so that the lower end just touches the floor. The chain weighs 2lb/ft. The upper end that is held is released from rest at t = 0 and the chain falls straight down. Ignore air resistance, assume that the +...

Question: Just give me hint of free body diagram where force will be considered because I have to find the force.I have tried this problem with past rules but now al little force problem so the question is Question: A man weights 180lb;the plateform and attached frictionless pully weigh a total...

A plane which is flying at constant speed v, and a height h, above the sea, must drop a bundle of supplies to a castaway of a small raft. a) write down Newtons second law for the bundle as it falls from the plane, assuming you can neglect air resistance. Solve your equation to give the...

if r, v, a denote the position, velocity, and acceleration of a particle, prove that d/dt [a . (v x r)] = d/dt(a) . (v x r ) (the periods between a and (vxr) denotes a dot product, and the actual question shows a dot over the a instead of d/dt(a) I know the point is that you get v x...

Homework Statement hi there, really don't know how to attempt this, could someone please give guidance, thanks. a crane needs a force of 3kN to lift a mass of 6 tonne. if the load is initially at rest and the maximum velocity is 5m/s, determine the time taken to lift the load. Any help would...

1. Two blocks are connected by a rope that passes over a set of pulleys. One block has a weight of 412N, and the other has a weight of 908N. The rope and the pulleys are massless and there is no friction. a.) What is the acceleration of the lighter block? b.) Suppose that the heavier block is...

im stuck with this problem: the question asked for the gravatational force of attraction between moon and Earth while the moon's radius is not given. do i need the moon's radius? since r is the distance from the center of moon to the center of Earth (right?) and the second question of the same...

Hello, I have a question with a simple Tension - Mass problem. Here is the question: For the systems in Equilibrium, find the unknown tensions and masses. a) http://answerboard.cramster.com/answer-board/image/ed663c5fcb01e8fb6c7522cf963b49f1.jpg b)...

I have a problem where I have an air cooled condensing unit located in a large room within a building. The volume of the room is approximately 27,195 cubic feet. The air cooled condensing unit rejects 102,600 btu/hr to the space. Assuming the ambient air temperature of the space is 95 degrees...

Hello, the question I'm having trouble with is: "A 8.00kg block of ice, released from rest at the top of a 1.5 m long frictionless ramp, slides downhill, reaching a speed of 2.5 m/s at the bottom. What is the angle between the ramp and the horizontal?" My first attempt to solve this...

Sorry people, not sure where I am going wrong, I am just not sure in which direction to take this question. I don't even know where to start. A box with mass of 22kg is at rest on a ramp inclined at 45 degrees to the horizontal. The coeffecient of friction between the box and ramp are (Static...

Hi I have a problem I need someone to check over and see if I have it right! Thank you for trying in advance Responding to an alarm, a 92kg fireman slides down a pole to the ground floor, 3.2m below. The fireman starts at rest and lands with a speed of 4.9 m/s. Find the average force...

I can't figure out how to solve for the minimal speed needed if they only provide me a radius. I am using this formula: \sqrt{\frac{F*r} {m} } I simplified to: \sqrt{g*\mu*r} ,but i don't have no idea how to solve for /mu . Please some help.

I have a block conected to another block by a string in an inclined surface, with a frictionless pulley. Both blocks are the same weight so i already figure the acceleration of the object that its being pulled up. What I don't know is how can I calculate the minimum kinetic friction that will...

I have a block conected to another block by a string in an inclined surface, with a frictionless pulley. Both blocks are the same weight so i already figure the acceleration of the object that its being pulled up. What I don't know is how can I calculate the minimum kinetic friction that will...

I'm stuck on the following question: Newton's law of universal gravitation is represented by the following equation. F = GMm/r2 Here F is the magnitude of the gravitational force exerted by one small object on another, M and m are the masses of the objects, and r is a distance. Force has...

http://www.boredofstudies.org/community/attachment.php?s=&postid=266675 when doing this question, isn't the radius of the planet supposed to be added to the altitude of the satellite? having said that, would the term 'orbit' mean that the satellite is 35 000km away from the centre of mass...