Law Of Motion Flashcards by Vinayagam ANN

_________Branch of physics that deal with the effect of force on bodies. it’s divided into

Mechanics

Statics and dynamics

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Statics

It deal with the bodies which are at rest under the action of force

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Dynamics

It is the study of moving bodies under action of force
Types
Kinematics
kinetics

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Kinematics

A deal with the motion of bodies without considering the cause of motion

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Kinetics

It deal with the motion of bodies considering the cause of motion

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Aristotle’s natural motion and violent motion

Natural motion
A natural state of earthly bodies is rest. he stated that every moving body naturally comes to rest without any external influence of the force

Violent motion
He also proposed that a force is needed to make the bodies to move from there natural state and behave contrary to their own natural state called violent motion

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When two different mass bodies are dropped from a height, the heavier body falls faster than the lighter one said by

Aristotle

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Galileo proposed the following concept about force motion and inertia of bodies

1 The natural state of earthly bodies is either the state of rest or the state of uniform motion
2 a body in motion will continue to be in the same state of motion as long as no external force is applied
3 when a force is applied on bodies they resist any change in their state. this property of bodies is called inertia
4 when dropped from a height in vacuum, bodies of different size, mass and shape fall at the same rate and reach the ground at the same time

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The inherent property of a body to resist any change in its state of rest or the state of uniform motion, unless it is influenced upon by an unbalanced force is known as

Inertia

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When the cardboard has moved, the coin falls into the Tumbler due to gravity. This happened due to

Inertia of rest

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Inertia of rest

The resistance of a body to change its state of rest is called inertia of rest

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Inertia of motion

The resistance of a body to change its state of motion is called inertia of motion

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Inertia of direction

The resistance of a body to change its direction of motion is called inertia of direction

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An athelete Run some distance before jumping. Because, this will help him jump longer and higher

Inertia of motion

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When you make a sharp turn while driving a car you tend to lean sideways

Inertia of direction

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When you vigorously shake the branches of a tree some of the leaves and fruits are detached and they fall down

Inertia of rest

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The impact of a force is more if the velocity and the mass of the body is more. To quantify the impact of a force exactly here new physical quantities known as

Linear momentum

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______ measures the impact of your force on your body

Linear momentum
P = m*a
It helps to measures the magnitude of a force

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The unit of momentum in SI system is______

The unit of momentum in CGS system is

1 kgms^-1
2 gms^-1

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The product of mass and velocity of a moving body gives the magnitude of _______________. It acts in the direction of the velocity of the object

Linear momentum

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Newton first law

Everybody continues to be in its state of rest or the state of uniform motion along a straight line unless it is acted upon by some external force. This gives the definition of force as well as inertia

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Type of force

Like parallel force; to our more forces of equal or unequal magnitude acting along the same direction, parallel to each other
Unlock parallel force: if two or more equal forces or Unequal forces act along opposite directions parallel to each other .

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When several forces act simultaneously on the same body then the combined effect of the multiple force can be represented by a single force termed as0

Resultant force
It is equal to vector sum of all the force

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If the resultant force of all the forces acting on a body is equal to zero then the body will be equilibrium. Such force are called

Balanced force

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If the resultant force is not equal to zero then it causes the motion of body due to

Unbalanced force

System can be brought to equilibrium by applying another force which is equal to the resultant force in magnitude but opposite in direction. Such force is called as

equilibrant

They rotating or turning effect of a Force about fixed point or fixed axis is called

Moment of the force or torque Torque = F*d F product of force D distance between the fixed point and the line of action of the force SI unit is Nm

To equal and unlock parallel forces applied simultaneously at two distinct points constitute a

couple Moment of couple M = F*S Couple results In causes the rotation of the body Rotating effect of a couple is known as moment of a couple Eg : Turning a tap, winding or unwinding a screw, spinning of a top

The unit of moment of a couple is In SI unit In CGS unit

Nm Dyne cm

The direction of moment of your force or couple is taken as positive if the body is rotated in _______ direction and negative if it is rotate in the ___________ direction

Anti clock wise Clockwise

Application of torque

Gear seesaw steering wheel

Principle of moments

When a number of like or unlike parallel force act on rigid body and the body is in equilibrium then the algebraic sum of the moments in the clockwise direction is equal to algebraic sum of moments in the anti clockwise direction. In other word at equilibrium the algebraic sum of the moment of all the individual forces about any point is equal to zero F1*D1=F2*d2

Newton's second law of motion

The force acting on your body is directly proportional to the rate of change of linear momentum of the body and the change in momentum take place in the direction of force This law help us to measure the amount of force so it is also called law of force F= (m (v-u))/t =m*a

SI unit of force CGS system

newton N Dyne

Definition of one newton

The amount of force record for a body of mass 1 kg produces and acceleration of 1 ms^-2 1N=1kgms^-2

Definition of 1 dyne

The amount of force required for a body of mass 1 gram produce an acceleration of 1 cm s^-2 1dyne=1gcms^-2 1N=10^5 dyne

Unit force

Amount of force required to produce in ascetes of 1 m s^-2 in a body of mass 1 kg is called unit force

Gravitational unit of Force

Hindi si system of unit gravitational unit of force is kilogram force represented by kg f. In the CGS system its unit is gram force is represted by g f 1kgf = 1kg*9.8ms^-2= 9.8N 1g f = 1g *980 cm s^-2= 980 dyne

Impluse

A large force acting for a very short interval of time J= F*t J=∆p

Impulse is also equal to the magnitude of

Change in momentum J=∆p Its unit is kgms^-1 or Ns

Change in momentum can be achieved in 2 ways

Your large force acting for a short period of time a smaller force acting for a longer period of time

Example of change in momentum

Automobiles are fitted with springs and shock absorbers to reduce jerks while moving on uneven road In cricket a fielder pulls back his hands while catching the ball. he experiences a smaller force for a longer interval of time to catch the ball resulting in a lesser impulse on his hand

Newton's third law

For every action the reason equal and opposite reaction. they always act on two different bodies Eg Birds fly Person swim firing of bullet

Law of conservation of linear momentum

m1v1 + m2v2 = m1u1 + m2u2

Propulsion of rockets is based on the law of

Law of conservation of linear momentum Newton third law of motion

Velocity which is sufficient to just escape from the gravitational pull of the earth . This velocity is called

Escape velocity

Newton's universal law of gravitation

This law States that every particle of matter in this universe attracts every other particle with a force. This forces is directly proportional to the product of their masses and inversely proportional to the square of the distance between the centre of these masses. The direction of the force acts along the line joining the masses F. = G m1 m2 --------------- r^2 G universal gravitational constant

SI unit of universal gravitational constant

N m^2 kg^-2

Mean (average) value of acceleration due to gravity

9.8 ms^-2 However the value of g is not the same at all point on the surface of the earth

Gravitation depends on the geometric radius of the earth Radius of the earth is maximum in the equatorial region and the minimum in the polar region The value of g is maximum in the polar region and the minimum at equatorial region

When you move to a higher altitude from the surface of the earth, the value of g reduces. In the same way when you move dip below the surface of the earth the value of g reduces. The value of g is zero at the centre of the earth

SI unit of weight

Newton

Direction of weight is always towards them ________ of the earth

Centre

Weight of your body varies from oneplace to another place on the earth.

since it's depends on the acceleration due to gravity of Earth(g) weight of your body is more at the poles than at the equatorial region

The value of acceleration due to gravity on the surface of the moon is

1.625ms^-2

The acceleration due to gravity on the surface of the moon is about ________ Times the acceleration due to gravity of Earth

0.1654

When the person in a lift most down with an acceleration (a) equal to the acceleration due to gravity (g), when a=g, this motion is called as___________ This condition refers to the state of ____

Free fall Weightlessness

astronauts are not floating But falling freely around them due to their huge orbital velocity

Space station and astronauts have equal acceleration they are under free fall condition. Hence both the astronauts and the space station are in the state of weightlessness

Dimensions of the heavenly bodies can be measured using

Newton's law of gravitation Eg Mass of the earth radius of the earth acceleration due to gravity can be calculated with the higher accuracy

________ helps in discovering new stars and planets

Newton law of gravitation

One of the irregularities in the motion of star called

wobble . Wobble leads to the disturbance in the motion of a planet nearby. In this condition the mass of the star can be calculated using the law of gravitation

_______ Helps to predict the path of astronomical bodies

Newton law of gravitation

_________is measured by the product of any one of the force and the perpendicular distance between two forces

Moment of couple

When a force F acts on a body for a period of time, then the product of force and time is known as

Impluse

The unit of gravity g is ms^-2, it can be also expressed as

Nkg^-1

At what height from the centre of the earth the acceleration of due to gravity will be 1/4th of its value as at the earth

From the centre of the Year the object is placed at twice the radius of the earth

Calculator velocity of a moving body of mass 5 kg whose linear momentum is 2.5 kg ms^-1

Linear momentum = mass *velocity Ans 0.5ms^-1

Door is pushed at a point whose distance from the Hinges is 90 cm with your force of 40N. Calculate the moment of force about the uses

Moment of force M = f * d Ans 36N

1 kg force equal to

98 x 10^4 dyne

The mass of a body is measured on planet earth as M kg. When it is taken to a planet of radius half that of the earth then it's value will be _____ kg

If the earth shirnks 50% of it real radius it mass remaining the same, the weight of a body on the earth will

Increased by 300%

Turning of tap ,winding or unwinding of screw and spinning of a top

Moment of couple

Which law gives the definition of force as well as inertia

Newton's 1st law

Which law help us to measure the amount of force so it is also called as law of force

Newton second law

The acceleration is produced along the radius called as The force which produce in this acceleration is called as

Centripetal acceleration Centripetal force

_______ is the weight of the body acquired due to action of gravity and other external force acting on the body

Apparent weight

The unit of g is m s^-2. It can be also expressed as

Nkg^-1

A man of 100 kg has a weight of _______ at the surface of earth

980N

Two bodies have a mass ratio of 3:4 The force applied on the bigger mass produces an acceleration of 12ms^-2. What could be the acceleration of the other body, if the same force acts on it.

F=ma 16 ms^-2