Applications of newton''s laws - ii, Physics


1.  As the body moves through the body it displaces the fluid. It has to exert a force on the fluid to push it out of the path. By the Newton's third law, the fluid pushes back on the body with an equal and opposite force. The direction of fluid resistance force on a body is always opposite to the direction of the body's velocity relative to the fluid.

The Newton's third law states that every action has equal and opposite reaction.

2. The magnitude of the fluid resistance force generally increases with the speed of the body through the fluid. Usually, f = kv (an empirical law). Suppose that you drop the ball bearing into a deep container filled with oil. After some time the ball bearing will approach its maximum (terminal) speed when the forces of gravity and friction balance each other:

mg = kv from which vfinal  = mg / k.


3. The above was easy instance of the equilibrium under two forces. Generally, while solving the problems you should 

a)draw a diagram,
b)define an origin for a system of coordinates,
c)identify all forces (tension, friction, normal, weight, etc) and their x and y components, d)Apply Newton's law separately along the x and y axes. e) find the accelerations, then velocities, then displacements. This sounds very easy task, and in fact it will happen to you naturally how to do this while solving the actual trouble.

4. Your weight in a lift: assume that you are in a lift which is at rest or is moving at constant velocity. In either case a=0 and the normal force N and the force due to gravity are exactly equal,

N Mg = 0 ⇒ N = Mg. But if the lift is accelerating downwards then the Mg - N = Ma or N = M ( g a) . Thus now the normal force (that is the force with which the floor of the lift is pushing on you) is decreased. Note that if the lift is accelerating or moving downwards with acceleration a then N=0 and you will experience weightlessness just like astronauts experience in space. Ultimately, if the lift is accelerating upwards then a becoms negative and you will feel heavier.

5. Suppose that you are in a railway wagon and want to know that how much you are accelerating. You are not able to look through the windows. A mass is hung from roof. Find the acceleration of car from the angle made by the mass.

2040_application of newton law4.png

6. Friction is a amusing kind of force. It does not make its mind which way to act until some other force compels it to make a decision. Assume a block lying on the floor. If you push it forward, friction will act backward. And if you push it to the left, friction will act to the hand side right. Or we can say that the direction of the frictional force is always in the opposite direction to the applied force.


7.  Let us solve the given problem: a rope of the length L and mass per unit length is placed on a table with a length l hanging from one edge. What should be l so that the rope just begins to slip?


826_application of newton law5.png

To solve this, look at the balance of the forces in the diagram given: in the vertical direction, the normal force balances the weight of the part of the rope the lies on the table:


N = m(L l ) g. In horizontal direction, the rope exerts the force mlg to the right, which is counteracted by the friction that which to the left. Therefore μ N = mlg. Substituting from the first equation we find out

l =       μ L

μ + 1

 Note that if μ is very small in measure then even a small piece of string which hangs over the edge will cause entire string to slip down.

Posted Date: 7/26/2012 2:31:18 AM | Location : United States

Related Discussions:- Applications of newton''s laws - ii, Assignment Help, Ask Question on Applications of newton''s laws - ii, Get Answer, Expert's Help, Applications of newton''s laws - ii Discussions

Write discussion on Applications of newton''s laws - ii
Your posts are moderated
Related Questions
Define one newton

A person is tasked with creating a ray diagram to resolve the characteristics of the image of an object formed by a concave lens. The person has accurately drawn the principal axis

Biot-Savart law (J.B. Biot, F. Savart) A law defines the contributions to a magnetic field through an electric current. This is analogous to Coulomb's law. Mathematically spec

i need to think of a project to assemble as soon as possible but i need some ideas.. what projects can i present??

CAPACITOR MEASUREMENTS : Many modern digital multimeters incorporate a capacitance measuring facility although this may be limited to just one or two ranges. The diagram below

Consider the sketch of the electromagnet in the figure below. Which components could you change to increase or reduces the strength of the electromagnet? Describe your answer.

Who shared the Nobel Prize in Physics in 1909 with Guglielmo Marconi for his contribution to the development of wireless telegraphy? Ans: (Carl Ferdinand) Braun shared the N

The topic for the project is to study and do calculation in Rotating Biological Contactor although you may choose a different title for your report. The aim is to research how the

What is seebeck effect. Illustrate how thermo emf varies with temperature in a thermocouple, describe neutral and invertion temperature. What are Thomson effects and Peltier? D

Two circular coils, one of radius r and the other of radius R are placed coaxially with their centres coinciding. For R >> r, get an expression for the mutual inductance of the arr