What is Laws of motion: Definition and 214 Discussions

Homework Statement For a birthday gift, you and some friends take a hot-air balloon ride. One friend is late, so the balloon floats a couple of feet off the ground as you wait. Before this person arrives, the combined weight of the basket and people is 1200kg , and the balloon is neutrally...

I've been lurking on PF for awhile now, but I reckon I'd benefit by actually trying to participate in the discussion and by asking my own questions once in awhile so, Hi all! In my second year I took a module on Classical Mechanics, and one of the things we covered was the Coriolis Theorem...

The first law of motion says that it takes force to accelerate something. The second law of motion says that F=ma. So now my teacher says that the first law is for inertial reference frames, while the second is for non-inertial reference frames. This really annoys me because I don't...

Homework Statement Find : a) acceleration of 1 kg, 2kg and 3 kg blocks and b) tensions T1 and T2 Note: In the figure, 1, 2 and 3 represent the masses of respective blocks in Kg. T1 and T2 represent tension in strings Homework Equations Newton's laws and constraint equations...

What is the magnitude of the force F (assumed horizontal) required to push the block up the plane at a constant speed? Take the coefficient of kinetic friction to be 0.25. Block is 75 lb I used Ff= mewN and found Wparallel Did Ʃ=ma Fapp-Ff-Wparallel= ma but i keep getting wrong answer

Net force and Newton's laws of motion! Homework Statement A barge is hauled along a straight-line section of canal by two horses harnessed to tow ropes and walking along the tow paths on either side of the canal. Each horse pulls with a force of 490 N at an angle of 19° with the centerline...

Homework Statement [PLAIN]http://img687.imageshack.us/img687/5055/imagelrl.jpg Homework Equations Static friction = (9.81sin60 x 0.2)N Centripetal force = mr(w)² The Attempt at a Solution I am only abl to get part (i), need hints for part (ii) and (iii). Thanks in advanced

I came across this question, " An 8000 kg engine pulls a train of 5 wagons, each of 2000 kg along a horizontal track. If the engine exerts a force of 40000 N and the track offers a frictions of 5000 N, then calculate the force exerted by wagon 1 on wagon 2." In this question,if we consider...

Homework Statement fill in the blanks. when a bird of weight W sits on a stretched wire, The tension in the wire is__________ Homework Equations Force(external)=mass*aceeleration The Attempt at a Solution tension should approach to infinity...

Homework Statement There are 2 blocks, one of mass m kept over other of mass 2m. Pls. refer to the diagram. The question is : the minimum value of u (coefficient of friction) between the 2 blocks for no slipping is : (a) F/mg (b) F/3mg (c) 2F/3mg (d) 4F/3mg My answer is coming as (b) but...

1. A fully loaded Saturn V rocket has a mass of 2.92 x 10^6 kg. Its engines have a thrust of 3.34 x 10^7 N. a. What is the downward force of gravity on the rocket at blast-off? b. What is the unbalanced force on the rocket at blast-off? c. What is the acceleration of the rocket as it...

A 325-kg boat is sailing 15.0° north of east at a speed of 2.00 m/s. Thirty seconds later, it is sailing 35.0° north of east at a speed of 4.00 m/s. During this time, three forces act on the boat: a 31.0N force directed 15.0° north of east, a 23.0N force directed 15.0° south of west and F Find...

1. A chain of mass M and length L is suspended vertically with its lower end touching a scale. The chain is released and falls onto the scale. What is the reading of the scale when a length of the chain x has fallen? You may neglect the size of the individual links. 2. A smooth wedge, whose...

Homework Statement A tractor is pulling a heavy weight behind it by a rope. If, according to Newton's third law, the load is pulling back as hard as the tractor is pulling forward, then why does the tractor move? Something else I don't really get: A fishline will break when a force of more...

Homework Statement Newton's 1st Law of Motion A ball rolled across the top of a pool table and slowly rolls to a stop. How would Aristotle interpret this behavior? Galileo? You? Newton's 2nd Law of Motion If a heavy person and a light person parachute together form the same altitude, and...

Homework Statement A 41-kg box is thrown at a speed of 235 m/s and is brought to a halt in a collision that lasts for a time of 6.8 ms. What is the magnitude of the average net force that acts on the box during the collision? Homework Equations Sum of Forces = m*a The Attempt...

Homework Statement An 18kg rock is released under water. The fricitional Buyoyance add up to 129N How long will it take to fall 1.0m Homework Equations The Attempt at a Solution

this is from chapter 4 of university physics of young and freedman q19 why can it hurt your foot more to kick a big rock than a small pebble? must the big rock hurt more? explain? but I can't see the answer at all by just applying Newtons law in the scenario of the small pebble mp is small...

Homework Statement 2 objects with mass m1=10 and m2=5 are connected by a light string that passes over a frictionless pulley, they are set up so that m1 is sitting on the desk and m2 is attached to a pulley, is over he desk. if when the system starts from rest, m2 falls 1 meter in 1.2seconds...

what is wedge constant and where and how to use it?

Homework Statement A block weighing 70.0 N rests on a plane inclined at 25.0° to the horizontal. A force F is applied to the object at 35.0° to the horizontal, pushing it upward on the plane. The coefficients of static and kinetic friction between the block and the plane are, respectively...

Homework Statement A car with a mass of 1100 kg is being pulled by a tow truck exerts a 500 N force on the car and there is a 300 N friction force acting on the car. If the car starts at rest at time t=0, at what time has the truck moved 100 meters? Homework Equations x=v0t + 1/2 at2...

Dear all I have come with a simple idea to generate the three laws of motion of Newton and would love to hear comments on its correctness. Assume equal point masses: the rule says ' the displacement of one point mass must be balanced by an equal and opposite displacement of another'. Since all...

Homework Statement What is the acceleration of the masses as shown in the second attached image. m1 = 0.9kg, m2 = 1.6kg, and m3 = 2.4kg. (Assume the table is frictionless) Homework Equations \sumF=ma F_mg+FN = ma The Attempt at a Solution I figured everything up to the point...

Homework Statement T here are 2 blocks connected by a string, as shown in the first image attached. The smooth inclined surface makes an angle of 40 degrees with the horizontal, and the block on the incline has a mass m1 = 7.9kg. What is the mass of the hanging block m2 that will cause the...

Homework Statement In the system shown all pulleys are light and smooth and all strings are light and inextensible. A block of mass m = 20 kg is attached to the movable pulley. A constant force, F, applied at the free end of the string, makes the point of application of force move down with...

I was checking online videos for lectures on kinematics and I watched one made by yale university but there was some part of it that I didn't understand when he talks about calculus derivation of Vf^2=Vi^2 + 2ax here is the video the derivation starts from about 1:08:45 I didn't understand...

Hi everyone! I am really bad in physics so I need help in my assignments. My problem is what formula to use. Here's the problems. Homework Statement An electron (mass = 9.11 x 10-31 kg) leaves one end of a tv picture tube with zero (0) initial speed and travels in a straight line to the...

Hello everyone, i need help with these 2 question from physics. I am a year 11 physics student. Joey and Caitlin hang from two ends of a wire, looped through an ideal pulley. Joey has a mass of 75.0Kg, whilst Caitlin weighs 637N. a) calculate the tension of the wire? b) If Caitlin is...

Homework Statement A crate pushed along the floor with velocity Vi slides a distance d after the pushing force is removed. a)If the mass of the crate is doubled but the initial velocity is not changed, what distance does the crate slide before stopping? Explain. b) If the initial...

A bike starts from rest. It covers a distance of 1km from rest to rest. If the minimum time in which the bike covers the distance is 100s, the coefficient of friction between road and tyre = ? s = (1/2)at^2 no idea how to go about it.

Two blocks placed one on top of the other are lying on a horizontal smooth surface. The coefficient of friction between the blocks is \mu. Case 1: Horizontal force F is applied to the lower block (Fig. 14). [PLAIN]http://www.monbattle.com/1.jpg Please help me to find out how they have...

View this attachment and tell me whether it is correct or not? It is written there that to move the block we need F Sin\theta > f_s. I agree but then they have given the value of f_s equal to \mumg. How can it be possible as we don't have any vertical motion.

Homework Statement Find θ and W in the figure below where w1 = 16.0 N, w2 = 25.0 N, and α = 66.5°, assuming that the arrangement is at rest. Homework Equations T_1=25/sin(alpha) F_x=-T_1cos(alpha)+T_2cos(theta) F_y=T_1sin(alpha)+T_2sin(theta)-2 The Attempt at a Solution I tried to...

Homework Statement A 65kg swimmer jumps of a 10m tower. a) Find the swimmer's velocity when hitting the water b) The swimmer comes to a stop 2.0m below the surface. Find the net force exerted by the water. Homework Equations F=ma? I don't know the rest, which is part of the problem...

Homework Statement A 1380kg car is moving due east with an initial speed of 27 m/s . after 8.00s the car has slowed down to 17.0 m/s . Find the magnitude and direction of the net force that produces the deceleration Homework Equations Net force of x= MAx Net force of y= MAy The...

Homework Statement To model a spacecraft , a toy rocket engine is securely fastened to a 2.00-kg large puck, which can glide with negligible friction over a horizontal surface, taken as the xy plane. The engine exerts a time-dependent force, F = (8.00 î – 4.00t ĵ) N, where t is in seconds...

A fisherman is fishing from a bridge and is using a "32.0-N test line." In other words, the line will sustain a maximum force of 32.0 N without breaking. What is the weight of the heaviest fish that can be pulled up vertically, when the line is reeled in with an acceleration whose magnitude is...

A toboggan slides down a hill and has a constant velocity. The angle of the hill is 8.80 with respect to the horizontal. What is the coefficient of kinetic frction between the surcae of the hill and the toboggan? So i used the formula: sum of forces(x)= cos (8.80)=0.98823 Forces (y)=...

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 A force of 38.64 N pushes and pulls two blocks as shown in the figure below. The vertical contact surfaces between the two blocks are frictionless. The contact between the blocks and the horizontal surface has a coefficient of friction of 0.18. The acceleration of...

I'm having a hard time with understanding this

Homework Statement For a birthday gift, you and some friends take a hot-air balloon ride. One friend is late, so the balloon floats a couple of feet off the ground as you wait. Before this person arrives, the combined weight of the basket and people is 1220 kg , and the balloon is neutrally...

When two people push in the same direction on an object of mass {\rm m} they cause an acceleration of magnitude a_1. When the same people push in opposite directions, the acceleration of the object has a magnitude a_2. Determine the magnitude of the force exerted by each of the two people in...

Hi all, I'm trying to get my head round how to apply Newtons laws and an exercise like a bench press, probably a bit simple to what you guys are used to. I want to make it as simple as possible to understand what forces would be acting during the eccentric phase of an exercise, I.e lowering...

I kinda need help on this question because i can't find any article or references and please explain how the 3rd law related to safety devices in cars. Question: Access the design and use of injury prevention devices in cars in terms of Newton's laws of motion.

Homework Statement A person on a snow sled(total mass of 60.0kg) starts from rest at a vertical height of 24.0m above the bottem of the hill. If aconstant frictional force of 70.0 N opposes their motion as they slide down the hill and the length of the slope is 65.0m, whta is their speedat the...

Three forces acting on an objetc are given by F1=(-2.00i + 2.00j)N, F2=(5.00i - 3.00j)N, F3=(-45.0i)N The object experiences an acceleration of magnitude 3.75 m/s2. a) What is the direction of the accceleration? b) What is the mass of the object? c) If the object is initially at rest, what is...

Homework Statement Due to a jaw injury, a patient must wear a strap (see the figure) that produces a net upward force of 5.00 N on his chin. The tension is the same throughout the strap. To what tension must the strap be adjusted to provide the necessary upward force? Homework...

Suppose the rocket is coming in for a vertical landing at the surface of the earth. The captain adjusts the engine thrust so that rocket slows down at the rate of 2.50m/s^2 . A 8.00-kg instrument is hanging by a vertical wire inside a space ship. 1]Draw a free-body diagram for the instrument...