Newtons Definition and 494 Threads

Homework Statement My teacher puzzled me in the beginning of the year by saying that one cannot possible hit a falling feather with 200 Newtons because a falling feather doesn't have 200 Newtons to hit you back with. (Newton's Third Law) Homework Equations None The Attempt at a...

Homework Statement A car weighing 15000N experiences a drag force of 1200N. The car travels 30m/s on a level highway. The coefficient of kinetic friction is 0.2. If the car travels for 10s at this speed, calculate the power the engine produces. The car then goes up a 10 degree constant...

Homework Statement Block A in the figure weighs 65.9N. The coefficient of static friction between the block and the surface on which it rests is 0.27. The weight w is 12.2N and the system is in equilibrium. block A is placed on a table, it is connected by a string to a wall block w is...

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 train consisting of two cars pulled by a locomotive experiences an acceleration of 0.33m/s^2 [fwd]. Friction is negligible. Each car has a mass of 3.1 * 10^4 KG. a. ) Determine the force exerted by the first car on the second car. b. ) Determine the force exerted by...

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...

Hi! So I thought I knew the laws of physics and electronics, but I've recently stumbled on to a puzzling bit of "Math vs Pratical application". I'm messing up the forces and equations in my strained little head, so I'll let you guys have a go. I'll go into practical applications of this...

NOTE Newtons first law does NOT seem to work here, at the object does NOT keep moving at a constant speed, it actually stops. Am I missing somthing ? Wayne

1. Hi really struggling with this question any help would be great. Use Newtons method to find the root of 4sin^2x - x = 0 which lies closest to [B]x=2, correct to 3sf. Homework Equations The Attempt at a Solution

Hello! In Newton's method, I am having difficulty understanding why the convergence is quadratic. I can imagine the closer and closer approximations moving along the x-axis as the base of a right angle triangle, but I cannot see from here how I arrive at the convergence being quadratic. Any...

Homework Statement A baseball of mass m is thrown vertically upward from a height r=0 with a speed of 20 meters/sec. The gravitational force on the baseball has a magnitude mg (m = mass, g=9.8 meters/sec2 is the acceleration due to gravity) and is directed downwards. Using Newton's second...

18. An elevator that weighs 3.5 x 103 N is accelerated upward at 1.0 m/s2. What force does the cable exert to give it this acceleration? A. 357 N B. 0 N C. 3500 N D. 3857 N (For this quesion I was really confused and I guessed that the force of tension in the cable was what the cable...

14. According to Newton’s _____ law, an object with no net force acting on it remains at rest or in motion with a constant velocity. A. Third B. Fourth C. Second D. First (for this question I related it to the concept of Newtons first law) Is this correct

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...

how do you find the Tension force,acceleration,magnitude. Its those questions where you have pullys,boxes pushing each other... I am really confused for the 3rd law

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...

Homework Statement A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is 0.18 and the push imparts an initial speed of 4.1 m/s? Homework Equations MG of the object = mass * 9.8 Friction = mg * 0.18 The...

Homework Statement Three crates are arranged. The masses of the crates are m1= 29.8kg, m2= 15.3kg, and m3=27.3kg. The applied force of 910 N is directed horizontally, and the coefficient of friction is u= .277. what is the acceleration of the three masses and the magnitude of the...

Homework Statement How much tension must a rope withstand if it is used to accelerate a 1000 kg car vertically upward at 0.80 m/s2? Ignore Friction. Homework Equations fay= ma ? mg-fn=0 The Attempt at a Solution F=MA F=1000kg * .8 F= 800 WRONG!

I was wondering, if Newton's third law is true why is there motion?

The figure shows two planets of mass m orbiting a star of mass M. The planets are in the same orbit, with radius r, but are always at opposite ends of a diameter. This is the equation eq. I used: mv^2/r=GMm/r^2+Gmm/(2r)^2 This is what I came up with but it is not the right answer. Where...

The pine tree air freshener hanging from the rear view mirror makes an angle of 27.9 degrees with the vertical while a car is acceleration a)What is the car's acceleration ax=gsin(theta)=9.80*sin(27.9)=4.59 b)What is the tension in the string of the 100g air freshener? ax=T/m=4.59(100)=T...

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...

So is it true that if you have a constant velocity therefore you have no change in acceleration so A=0 and if you have no acceleration then you have no Fnet? And is that the case in ANY force problem? Thanks!

I'm going to write this up the same way my teacher gave me the sheet Homework Statement At 9am on october 19, 2009 a body was found in room 327 at University Center. The room is kept at a constant temperature of 72 degrees. The medical examiner was called and he arrived in eight minutes...

I'm going to write this up the same way my teacher gave me the sheet Homework Statement At 9am on october 19, 2009 a body was found in room 327 at University Center. The room is kept at a constant temperature of 72 degrees. The medical examiner was called and he arrived in eight minutes...

Homework Statement Hi guys i am trying to do question number 4 but i have not done a Question liek this in a very long time so i am forgetting where to start. http://img405.imageshack.us/img405/6976/101420092845.jpg" Image is to big for the forum so its easier that way. Homework Equations...

Homework Statement I've been given a problem that an object falls from a distance of 800 feet with an initial velocity of 4 f/s. Gravity acts on the object, but air resistance can be disregarded. Find the location at time t and find when the object hits the ground. The Attempt at a...

Homework Statement A curve of radius 16 m is banked so that a 940 kg car traveling at 44.4 km/h can round it even if the road is so icy that the coefficient of static friction is approximately zero. You are commissioned to tell the local police the range of speeds at which a car can travel...

Homework Statement a box of Cheerios (mass mC = 1.1 kg) and a box of Wheaties (mass mw = 3.6 kg) are accelerated across a horizontal surface by a horizontal force applied to the Cheerios box. The magnitude of the frictional force on the Cheerios box is 1.6 N, and the magnitude of the...

Homework Statement There is a drawing with a block weight 416N on a table attached to a string that is running through a pulley at the end of the table. On the other end of the string a block that is hanging off the side of the table with a weight of 215N. Ignore all frictional effects and...

** sorry. this would be Newtons 2nd law of motion. oops. Homework Statement Hockey puck with mass 0.160kg at rest at x=0 and t=0 on horizontal frictionless surface. hockey player applies force of 0.250 N until t = 2.00s. ... ... if the same force is applied again at t = 5.00 s what is the...

Homework Statement Two boxes are in contact with each other, both different mases, and are both being pulled by an external force, F. M1M2--------->F I can calculate the acceleration of the system but the Question asks to calculate the force between the mases, ie Newtons third law. If...

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...

1. In the drawing, the weight of the block on the table is 388 N and that of the hanging block is 175 N. Ignore all frictional effects, and assuming the pulley and the cord to be massless. Find the acceleration of the two blocks as well as the tension in the cord 2. Fnet = mass of the...

Homework Statement At the airport, you pull a 18-kg suitcase across the floor with a strap that is at an angle of 45 deg above the horizontal. Find a) Normal force and b) the tension in the strap, given that the suitcase moves with constant speed and that the coefficient of kinetic...

Homework Statement Paleontologists estimate that if a Tyrannosaurus rex were to trip and fall, it would have experienced a net force of approximately 256,700 N acting on its torso when it hit the ground. Assume the torso has a mass of 3710 kg. (a) Find the magnitude of the torso's upward...

Homework Statement The coefficient of static friction is 0.60 between the two blocks in figure. The coefficient of kinetic friction between the lower block and the floor is 0.20. Force causes both blocks to cross a distance of 5.0 m, starting from rest. What is the least amount of time in...

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...

Homework Statement A person jumps from the roof of a house 4.4 m high. When he strikes the ground below, he bends his knees so that his torso decelerates over an approximate distance of 0.70 m. The mass of his torso (excluding legs) is 40 kg. (a) Find his velocity just before his feet...

Homework Statement In figure 6-36, two blocks are connected over a pulley. The mass of block A is mA and the coeffcient of kinetic friction between A and the incline is Uk. Angle of the incline is theta. Block A slides down the incline at constant speed. What is the mass of block B? Express...

A 20000 rocket has a rocket motor that generates 3.0×105 of thrust. What is the rocket's initial upward acceleration? Express your answer using two significant figures. At an altitude of 5.0 km the rocket's acceleration has increased to 6.0 m/s^2 . What mass of fuel has it burned...

how large is the normal force? (applying Newtons laws phys 1111) A 23 kg child goes down a straight slide inclined 38 degrees above horizontal. The child is acted on by his weight, the normal force from the slide, kinetic friction, and a horizontal rope exerting a 30 N force as shown in the...

this is from ch 4 of cutnell & johnson physics when you add forces together such as the ones in the problem below, how do you know which ones are positive and which ones are negative? does it have to do with their relation on the xy axis? or does it have to do with the direction the object is...

Homework Statement A thermometer reading 70o F is placed in an oven preheated to a constant temperature. Through a glass window in the over door, an observer records that the thermometer reads 110o F after 1/2 minute and 145o F after 1 minute. How hot is the oven.Homework Equations...

I have a scenario which is simply a ball hits the ground from above i know the mass of the ball and the speed in mph of the ball just before it hits the ground. No other variables are known, I need to know the force it hits the ground. What is the best way to calculate it? I had thought F =...

Newtons universal constant is very complicated due to that i am new to modern Earth science i searched on the net and the results were countless here is the common answer 1-G=6.67*10(squared negative 11)m(cubed)kg(squared negative 1)s(squared) someone please tell me what all this means and how...