# Question: Why Second And Fourth Angle Projections Are Not Used?

## What is angle of projection for maximum horizontal range?

(1) where U is the initial velocity, θ is the angle of projection and g is the acceleration due to gravity.

The horizontal distance covered by the projectile i.e.

range is given by, R=U2Sin2 θ g…

(2).

Hence the angle of projection should be 36.86 degrees..

## Why we use only 1st and 3rd angle projection?

Europe had used the method of first angle projection in creating orthographic views of three-dimensional parts for manufacturing for many decades, while in the U.S., engineers had settled on using third angle projection with its more logical placement of views.

## What is symbol of Third Angle Projection?

When view are drawn in their relative position Top view comes above Front view, Right side view drawn to the right side of elevation. A Third Angle Projection drawing is identified by the third angle projection symbol. The angle of projection symbol typically appears in angle of projection block near to Title block.

## How do you find angle of projection?

In case of a projectile motion, if the range R is n times the maximum height H then the angle of projection θ is equal to tan−1(n4​)

## What is the difference between 1st and 3rd angle drawings?

To get the first angle projection, the object is placed in the first quadrant meaning it’s placed between the plane of projection and the observer. For the third angle projection, the object is placed below and behind the viewing planes meaning the plane of projection is between the observer and the object.

## Which angle of projection is most commonly used?

The two orthogonal projection methods used internationally are first angle projection and third angle projection. Third angle projection (figure 1.2) is used mainly in The United States and Canada whilst first angle projection (figure 1.1) is used mainly throughout Europe and the rest of the world.

## What is angle of projection?

Answer: The angle at which an observer draw an object to convert it from 3D to 2D plane such as real object image to a plane paper is known as angle of projection. There are two angle of projection used in drawing: 1st angle of projection(first quadrant of coordinate plane)

## What are the 3 planes of orthographic projection?

The plane, horizontal or vertical, which are kept perpendicular to each other are called Principal Planes. These include the Frontal Plane, Profile Plane, and Horizontal Plane: In addition to this, if a plane is placed at any other place, then it is called Auxiliary Plane.

## Why orthographic projection is used?

Similarly with engineering, architecture, and design, a 3D drawing does not show enough detail—orthographic projections help overcome that problem. An orthographic projection is a way of representing a 3D object by using several 2D views of the object. Orthographic drawings are also known as multiviews.

## Why 3rd angle projection is used?

In the third angle projection, the object is placed in the third quadrant. The object is placed behind the vertical planes and bottom of the horizontal plane. Third angle projection is widely used in the United States. The projection planes come between the object and observer.

## How do you read 1st and 3rd angle drawings?

For the first angle projection, place the object in the first quadrant and in the third quadrant for the third angle projection. The object is placed between the plane of projection and observer for the first angle projection and between the object and observer for the third angle projection.

## Which projection is used in India?

Lambert Conformal Conic Projection systemThe Indian Grid uses the Lambert Conformal Conic Projection system (also known as Conic Orthomorphic Projection) with 2 Standard Parallels.

## What is 2nd and 4th angle projection?

In 2nd and 4th angle projection system, the top and front views are overlap to each other. In 2nd angle projection system, the plane is in between object and observer. When we turn the adjacent plane by 90 degree to see the top view, the front and top views are overlap to each other.

## Who uses 3rd Angle Projection?

The US, Canada, Japan and Australia are the only other regions that typically use 3rd Angle projection as standard. 3rd Angle project is where the 3D object is seen to be in the 3rd quadrant.

## What is 1st angle of projection?

First angle projection is a method of creating a 2D drawing of a 3D object. … This is important information for the person interpreting the drawing because if you examine the diagram below you will note that in first angle orthographic projection: the view from the front is in the middle.

## How do you do first angle projection?

Drawing a first angle orthographic projectionStep 1 – Begin by drawing light pencil lines to create the boxes that will contain the front elevation and the plan.Step 2 – Draw a 45º line from the front elevation box. … Step 3 – Draw the front elevation in its box.Step 4 – Project lines from the front elevation to construct the plan.More items…