How Do You Describe Force and the Laws of Motion?Newton’s Laws of Motion

They describe the relationship between a body and the forces acting upon it, and its motion in response to said forces.

1643 - 1727

First Law(Law of Inertia)

An object that is at rest will stay at rest unless an external force acts upon it.An object that is in motion will not change its velocity unless an external force acts upon it.

Second LawF = m × a

The acceleration of a body is directly proportional to, and in the same direction as, the force acting on the body, and inversely proportional to its mass

a = F/m

A force is any influence that causes an object to undergo a certain change, either concerning its movement or direction. In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate.

The Unit of Force is the Newton (N)

Definition: The amount of force needed to accelerate 1 kilogram of mass at the rate of 1 meter per second squared

Newton = kilogram (meter/second)/second1N = 1kg m/s2

Third Law

When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body.

Momentum

Definition: product of the mass and velocity of an object

p = mv

Units: kilogram meter/secondkg m/s

Newton’s Law of Universal Gravitation

Every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

G is the gravitational constant

Calculation of Force Between the Earth and a 1kg Rock 10meters High

F = Gm1xm2/r2

G = 6.674x10-11Ns2/kgM1 = 5.972x1024kg

M2 = 1kg

r = 6.341x106mr2 = 4.059x1013m2

F = 9.8Na = F/m =9.8N/1kg = 9.8m/s2