What is Newton's law: Definition and 351 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.
In Figure 6-63, a block weighing 22 N is held at rest against a vertical wall by a horizontal force of magnitude 60 N. The coefficient of static friction between the wall and the block is 0.55, and the coefficient of kinetic friction between them is 0.38. In six experiments, a second force is...
Homework Statement
[PLAIN]http://img208.imageshack.us/img208/9987/forcediagram.png
In the figure above, two small objects (magnets for instance) of the same mass exert forces on each other of a magnitude F. When object A is subjected to an external force of 3.6x10^-2 N, A accelerates at...
A block of mass m1 = 4 kg is put on top of a block of mass m2 = 5 kg. To cause the top block to slip on the bottom one while the bottom one is held fixed, a horizontal force of at least 12N must be applied to the top block. The assembly of blocks is now placed on a horizontal, frictionless...
A 75 kg person is standing on a bathroom scale in an elevator. The scale is calibrated to read in Newtons. The elevator is accelerating upward at 135 m/s2. What is the reading on the scale? What apparent value of g does the man give?
The Free Body Diagram
Normal on the man, upward...
While moving in, a new homeowner is pushing a box across the floor at a constant velocity. The coefficient of kinetic friction between the box and the floor is 0.41. The pushing force is directed downward at an angle θ below the horizontal. When θ is greater than a certain value, it is not...
Homework Statement
A child holds a sled on a frictionless, snow-covered hill, inclined at an angle of 25 degrees.If the sled weighs 56 N, find the force exerted on the rope by the child.
Homework Equations
\SigmaF=ma
The Attempt at a Solution
I set up a right triangle with 56N as...
Hi all,
I've been reading the Feynman Lectures on Physics and I've stumbled on something. I understand the theory but not how they arrived at the answer. It's to do with firing a bullet from a gun and working out the speed it would need to travel in a curve around the Earth's surface in order...
1. LAW OF COOLING PROBLEM!HELP PLEASE! :)
At 1:00pm, Sally puts into a refrigerator a can of soda that has been sitting of temperature 70degF. The temperature in the refrigerator is 40degF. fifteen minutes later 1:15pm, the temperature of the soda has fallen to 60degF. At some time later, Sally...
Homework Statement
at t=0; thermometer reading (x) =80 F (taken outside where the air temp is 20 F)
at t=3; x=42 F
then the thermometer is brought inside where the air is at 80 F.
at t=10; x=71 F
When was the thermometer brought indoors?
Homework Equations
temp=ambient temperature; x= present...
Air rushing over the wings of high-performance race cars generates unwanted horizontal air resistance but also causes a vertical downforce, which helps the cars hug the track more securely. The coefficient of static friction between the track and the tires of a 690-kg race car is 0.87. What is...
High guys,
I've always had problems with this law at the way it was explained.But now I've seen lewin explaining that way that bothers me: In terms of sensations.At 1:50
http://youtu.be/M_8w-dD4RBE
What I think is that we "feel" the pull only because we are made of multiple particles...
Homework Statement
A smooth wedge, whose central cross-section is a triangle ABC, right-angled at C, rests with the face containing AB on a smooth horizontal plane. When the wedge is held fixed, a particle released from rest, takes a time t1 to slide the full length of CA. The corresponding...
Hi All,
I am hoping to create an equation which I can use to describe the thermodynamic properties of microhabitats used by Chuckwalla lizards. Basically,the habitat in question is a crevice that is shaped like a rectangular prism within an igneous rock. I am trying to develop an equation that...
hi everyone...
i was recently thinking about a generator that would work as per the principle of electrostatics, the capacitor in specific...
the system i had thought of had two parallel charged capacitor plates with air as the dielectric medium and with minimum leakage current... between...
Homework Statement
Answers: 56. 6.16 x 10^17 N, 57. 894 N
Homework Equations
Fg = G*m1*m2/r^2
g = G*M/r^2
The Attempt at a Solution
56. Since the closest planet to Z is Y I figured the gravitational force could be calculated by just finding the gravitational force between Z and Y...
How do you approximate the ellipse of an object's orbit using Newton's law of universal gravitation?
I'm working on a 2D space game and that's pretty much the only physics I use, so no other forces to consider.
Work energy or Newton's law?
I have a question and solution(from book) too:
Question:
A force of 1.50N acts on a 0.20kg cart so as to accelerate it along an air track. The track and force are horizontal and in line. How fast is the cart going after acceleration from rest through 30cm, if...
Hi, I'm new here and I hope I'm posting in the right place. I have a question regarding Newton's Law of Gravitation, and it involves the formula:
F = GMm/r^2
You know, where F = Force of Gravity, G = 6.67e-11N*m^2, then M and m are two masses, and then r is the distance between the two masses...
Homework Statement
At 1:00PM, a thermometer reading 70oF is taken outside where the air temperature is -10oF. At 1:02PM, the reading is 26oF. At 1:05PM, the thermometer is taken back indoors, where the air is at 70oF. What is the temperature reading at 1:09PM?
Homework Equations
The Attempt at...
I'm having trouble with part a) of this question...
[PLAIN]http://img69.imageshack.us/img69/5815/98157006.png
So I started off by solving the DE above a), and I've gotten it down to:
\frac{1}{2} m v^{2} = \frac{mgR^{2}}{(x + R)} + C
I can tell I'm getting close, but I'm a little...
Homework Statement
A small metal bar, whose initial temperature was 20 degrees C is dropped into a large container of boiling water. How long will it take the bar to reach 90 degrees C if it is known that its temperature increases 2 degrees in 1 second. How long will it take the bar to reach...
Given F is directly proportional to the product of m1 and m2. F is also inversely proportional to the r^2. F, m1, m2 and r are real numbers.
Why we can link the above two variations together and say that F=km1m2/r^2, where k is the proportionality constant? Aren't the the variations...
I am struggling to understand Newtons law:
F = ma = GMm/r^2
a = GM/r^2
In the above equation, the small m's cancel out to give a constant acceleration due to gravity from the perspective of big M. I consider a planet and a small moon (little m) a certain distance away from the planet...
Homework Statement
First a glass of milk is put outside the refidgerator to heat, and its temperature changes from 6 degrees C to 13 C after two hours. When the temperature of the milk is 15 C the glass is put inside a refridgerator.
the problem is to find the ambient temperature in a...
Homework Statement
During a solar eclipse, the Moon, the Earth, and the Sun all lie on the same line, with the Moon between the Earth and the Sun. (a) What force is exerted by the sun on the moon? (b) What force is exerted by the Earth on the Moon? (c) What force is exerted by the sun on the...
Homework Statement
After a spacewalk, a 7-kg tool is left 54 m from the center of gravity of a 21-metric ton space station, orbiting along with it. How much closer to the space station will the tool drift in two hours due to the gravitational attraction of the space station?Homework Equations...
Extending Newton's Law to real life. No more "ideal systems"!
Homework Statement
Newton's Laws in reality, applying all forces 10 pts?
A block of mass m is hung on a pulley that is at the end of a table. The pulley connects the hanging block m and another block M that is on the table. The...
Homework Statement
Newton's Law of Cooling states that the rate of cooling of an object is proportional to the temperature difference between the object and its surroundings. Suppose t is time, T is the temperature of the object, and Ts is the surrounding temperature. The following...
I have used Newton's law of restitution without problem in collisions between point objects but there seems to be a problem in its application in eccentric impacts.
I have always thought it is applied to points on rigid extended bodies that come in contact during the collision for eccentric...
Homework Statement
A boy is pushing a lawnmower (25kg) with 200N of force on a handle that is angled 35 below the horizontal. The mower is accelerating at 0.9m/s^2. If the boy would like to maintain a constant velocity, what force does he need to apply to the mower handle.
Assume g = 9.8 [d]...
Homework Statement
Suppose that the temperature of a pan of warm water obeys Newton's law of cooling. The water (47 degrees Celsius) was put in a room and 10 minutes later the water's temperature was 40 degrees Celsius. After another 10 minutes, the temperature of the water was 34 degrees...
Homework Statement
Starting from the modified Newton's Law
(dp(rel))/dt=F
with a constant Force F, and assuming that the particle starts with v=0 at time t=0, show that the velocity at time t is given by
V(t)=c [(Ft/mc)/(1+ Ft/mc)]
Homework Equations
The Attempt at a...
Homework Statement
A man was murdered and inspectors found his body temperature to be 88 degrees at 4:30AM.
Climate control in the room was set to 76 degrees.
Temperature of his body was taken again 2 hours later and found to be 85.8 degrees.
The standard body temperature for human...
Homework Statement
A proud angler hangs her catch from a spring balance, which is supported from the roof of an elevator.
a.) if the elevator has an upward acceleration of 2.45m/s2 and the balance reads 50.0N, what is the true weight of the fish?
b.) Under what circumstances will the balance...
Homework Statement
I am doing a lab-"Kepler's Laws and Newton's Law of Universal Gravitation". There is an image representing various positions, at equal intervals, of a satelitte in an elliptical orbit around the earth. A list of planets and their radi and periods are given. I have calculated...
1. Take the equation F=[G(m1)(m2)]/r2
2. Assume a single mass of 20 (units don't matter), which will be divided in the following ways:
2.1. System 1: m1=20, m2=0
2.2. System 2: m1=19, m2=1
2.3. System 3: m1=18, m2=2
2.4. System 4: m1=17, m2=3
.
.
.
2.11.System 11: m1=10, m2=10
Now...
3...
Homework Statement
The lower chamber of the heart, (the left ventricle) pumps blood into aorta. The left ventricular contraction lasts 0.20 seconds, during which time a mass of 88 grams of blood is accelerated from rest to a speed of about 4.5 m/s. Find the acceleration & Force.
known:
V...
I'm somewhat familiar with the formula:
T(t)=T_{0}+(T_{i}-T_{0})e^{kt}
However, what if the ambient temperature is not constant? How would one find the temperature of an object with an ambient temperature that ramps from A to B (steady ramp let's say)?
I'm honestly not sure how to...
Newton's third law says that for every action force there's a simultaneous reaction force equal in magnitude to the action force, but in the opposite direction. So doesn't that make the net force zero? If that's true how does anything move?
Hi, I have a graph of T-TR vs. Time. These values were given to us for an assignment. However, the question then says using these values, "show" that it obeys Newton's Law of Cooling.
I can't ask my teacher because it's meant to be done on your own but show means many things to me.
Does...
why the Newton's law of motion are only valid in inertial frame of reference, not in non-inertial frame? since force like Coriolis force are not considered for these laws.
Being possibly the newest member here, I would like to put a question that has troubled my mind for quite a while..
If I have a uniform ring (having a certain mass) and a point mass in some idealised gravity free space & I orient them such that the point mass lies exactly at center of the...
After picking up passengers, a train accelerates uniformly until its speed is 100 km/hr at t= 300 s. If during this time it is traveling on a planar path that approximates the circle and line shown in the figure, find the magnitude of the train's acceleration when (a) t = 1 min and (b) t = 2...
Homework Statement
A train consists of three coaches A,B and C linked together via tow bars. A and C are coaches with engines and have a mass of 10000kg each, while B is an un-powered coach having a mass of 8000kg. The driving force of the engines in A and C are 20000N and 18000N respectively...
Newton's Law of Cooling (diff eq. -- separation of variables)
Homework Statement
Fresh coffee sitting in a room cooling...you know the routine.
Anyhow T(0) = 90degreesCelcius.
Room temp=25degrees Celcius
find k.
Then he asks us to use Euler's method to estimate coffee temp after five...
An astronaut weighs 99.3 N on the surface of the moon. If the same astronaut orbits the moon at an altitude equal to the moons radius, what gravitational force (in N) does the moon exert on him at this altitude?
can anybody get me going in the right direction? thanks
When a falling meteor is at a distance above the earth’s surface of 3.61 times the Earth's radius, what is the acceleration of the Earth's gravity in m/s2? (Use the average radius of the Earth in your calculations)
can somebody walk me through this one? thanks