What is Newtons laws: Definition and 121 Discussions
In classical mechanics, Newton's laws of motion are three laws that describe the relationship between the motion of an object and the forces acting on it. The first law states that an object either remains at rest or continues to move at a constant velocity, unless it is acted upon by an external force. The second law states that the rate of change of momentum of an object is directly proportional to the force applied, or, for an object with constant mass, that the net force on an object is equal to the mass of that object multiplied by the acceleration. The third law states that when one object exerts a force on a second object, that second object exerts a force that is equal in magnitude and opposite in direction on the first object.
The three laws of motion were first compiled by Isaac Newton in his Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), first published in 1687. Newton used them to explain and investigate the motion of many physical objects and systems, which laid the foundation for Newtonian mechanics.
Homework Statement
A duck has a mass of 2.30 kg. As the duck paddles, a force of 0.124 N acts on it in a direction due east. In addition, the current of the water exerts a force of 0.222 N in a direction of 50.3° south of east. When these forces begin to act, the velocity of the duck is...
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...
Homework Statement
1. what happened to the amount of friction between the surface and the shoe was the force of gravity was increased?
2. when a piece of paper was placed between the shoe and the surface(table), was more force, less force, or the same force needed to pull the shoe...
Homework Statement
[PLAIN]http://img28.imageshack.us/img28/7341/capturehzm.jpg
Homework Equations
Fg=mg
Ft=ma
Ftx=Ftsin(22)
Fty=Ftcos(22)
Fg-Fty=? I realize this is probably required but I don't know where.
The Attempt at a Solution
I believe the acceleration the question is...
Homework Statement
A 2.0 kg mass , placed on a smooth, level table, is attached by a light string passing over a frictionless pulley to a 5.0 kg mass hanging freely over the edge of a table. Calculate...
a) the tension in the string
b) the acceleration of the 2.0 kg mass on the table.The answer...
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...
For the following question:
A magician pulls a tablecloth out from under some dishes. *How far do the dishes move during the .25 seconds it takes to pull out the tablecloth? The coefficient of kinetic friction between the cloth and the dishes is .12
I think I got the answer right by...
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...
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
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
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!
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...
Homework Statement
What is the acceleration of a 35 kg block of cement when pulled sideways with a net force of 150 N?
Homework Equations
what i did was f=ma
a=m/f
and just plugged the numbers in
The Attempt at a Solution
i got 4.2 but when i entered it into the assignment it...
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...
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
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...
Homework Statement
In the figure, a crate of mass m = 96 kg is pushed at a constant speed up a frictionless ramp (θ = 27°) by a horizontal force F. The positive direction of an x-axis is up the ramp, and the positive direction of a y-axis is perpendicular to the ramp. (a) What is the magnitude...
applying Newtons laws on an inclined surface with two masses
Homework Statement
Two blocks connected by a cord passing over a small, frictionless pulley rest on frictionless planes (diagram attached)
a) which way will the system move when the blocks are released from rest?
b) what is the...
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...
Homework Statement
A mouse and an elephant are on a perfectly flat ice rink (no friction). 10N of force is applied to each animal for 10 seconds, describe their behaviour.
Homework Equations
F=ma
The Attempt at a Solution
Both animals will accelerate immediately and continue...
Homework Statement
An airplane is flying in a circle at a speed of 480km/h. It wings are tilted at 40 degrees to the horizontal. What is the radius of the circle in which the plane is flying? Assume that the required for is entirely provided by "aerodynamic life" that is perpendicular to the...
Homework Statement
a girl is skiing down a 35 degree inclined hill that is 120 meters long. She starts from rest and the snow has a coefficient of friction of .12.
A. Draw an FBD
B what is her acceleration
c. How much time dows it take her to travel the 120 meters
Homework Equations...
1. The only force on a 5.0 kg object has components Fx= 20N and Fy= 30N
2. Find the acceleration of the object and its direction of movement.
3. I think I'm supposed to somehow use Soh Cah Toa inorder to find something (I don't know what this would help me find). I need to use...
I attached the problems here. I am really having a tough time getting these problems started. Any help to get me going in the right direction would be great.
Homework Statement
I am a bit confused about what are inertial reference frames and what is not. The text states:
"We define an inertial reference frame as a reference frame in which Newton's laws are valid... Accelerating reference frames are not inertial reference frames...
Homework Statement
73) A cyclist is coasting at a steady speed of 12m/s but enters a muddy stretch where the effective coefficient of friction is 0.60. Will the cyclist emerge from the muddy stretch without having to pedal if the mud lasts for 11 meters?. If so, what will be the speed upon...
Dear all, I hope you could help me out a little.
Homework Statement
A person tries to raise a chain of 3 identical links; where each of the links has mass m.
The chain is connected to a string is suspended vertically with the person holding the upper end of the string and pulling upward...
Homework Statement
A 75kg climber is supported in a "chimney" by the friction forces exerted on his shoes and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are .8 and .6, respectively. what is the minimum normal force he must...
Homework Statement
A 2.8 kg wood block is launched up a wooden ramp that is inclined at a 34° angle. The block’s initial speed is 8.56 m/s. What vertical height does the block reach above its starting point?
What speed does it have when it slides back down to its starting point...
Homework Statement
A 26.21 kg loudspeaker is suspended 1.15 m below the ceiling by two 3.91-m-long cables that angle outward at equal angles. What is the tension in the cables?
Homework Equations
I have no idea
The Attempt at a Solution
well i know that i have the weight which is...
Is it possible to hate Newtons Laws?
Hi,
I am taking a course in physics, and I have noticed that Newtons Laws, and Newtons Mechanics just bores me to death whenever I am reading about it or trying to do questions.
On the other hand, we started to do some Energy and Work chapters, and the...
Joe was driving on the highway a car ahead of him was driving far below the speed limit so he decided to pass. In the first second he gained(gained means to get nearer to something you are chasing) 5m on the car and as he accelerated he gained 1.5 times as much distance in each second as he had...
[b]1. A figure shows an overhead view of a lemon half and two of the three horizontal forces that act on it as it is on a frictionless table. Force F1 has a magnitude of 4.70 N (in the negative x and positive y direction) and is at θ 1 = 29°. Force F2 has a magnitude of 7.00 N (in the positive x...
A red box and a blue box sit on a horizontal, frictionless surface. When horizontal force F is applied to the red box, it accelerates 4.88 m/s2.
a) If F is applied to the blue box, it accelerates at 1.32 m/s2. What is the ratio of the masses of the boxes (mass of the red box/mass of the blue...
A rope is tied to a 97.8 kg log. When you pull on the rope with a horizontal force of magnitude 706 N, the log moves at constant speed.
a) Find the magnitude of the resistive (frictional) force acting on the log. You may assume the frictional forces acting on the log is constant.
N
b)...
I have this problem on a web assignment due on the 20th of this month. A few of the problems have completely blown my mind including the following:
A force F0 causes an acceleration of 18 m/s2 when it acts on an object of mass m sliding on a frictionless surface. Find the magnitude of the...
Homework Statement
A block A (mass 2.25k) rests on a tabletop. It is connected by a horizontal cord passomg over a light, frictionless pulley to a hanging block B (mass 1.3kg). The coeffisient of kinetic friction between block A and the tabletop is 0.45. After the block is released from the...
My teacher asked us too prove that Hamiltons principle proves that Newtons equations of motion hold for N particles. I'm not sure that i fully grasp the concept but this is my understanding so far:
Using the lagrangian we can prove Newtons law for specific situations, however Hamiltons...
Homework Statement
1) The coefficient of kinetic friction for a 22-kg bobsled on a track is 0.10. What force is required to push it down at a 6.0 degree incline and achieve a speed of 60 km/h at the end of 75 m?
2) A box is given a push so that it slides across the floor. How far will it go...
[SOLVED] Newtons Laws Questions
Question: A 3 kg block moves up a 40 degrees incline with constant speed under the action of a 26-N force up and parallel to the incline. What magnitude force must act up and parallel to the incline for the block to move down the incline at constant velocity...
You have a bucket filled with water. A spring has been soldered to the bottom of the bucket, and a cork is attached to the other end of the spring. The cork is suspended motionless under the surface of the water. You are standing on a stationary elevator holding the bucket. The elevator then...