# Engineering Drawing Questions and Answers – Centres of Gravity – 1

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This set of Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Centres of Gravity – 1”.

1. Which of the following is not the definition of center of gravity?
a) A point on which whole weight if body balances
b) A point through which the resultant of forces of gravity of every particle in body acts
c) It is also called center of mass
d) The point in the body where the gravity becomes zero

Explanation: The center of gravity is defined as point on which whole weight if body balances (or) a point through which the resultant of forces of gravity of every particle in the body acts. It is also called center of mass. It may not necessarily lie within the body.

2. The center of gravity of a triangle is on ______
a) centroid
b) circum center
c) in center
d) ortho center

Explanation: The center of gravity is defined as point on which whole weight if body balances (or) a point through which the resultant of forces of gravity of every particle in body acts. For planar objects like triangle the center of gravity will be at its centroid.

3. Given steps in procedure to find the center of gravity of the quadrilateral ABCD. Arrange the steps.
i. Draw lines joining G1 with G2 and G3 with G4.
ii. In given quadrilateral draw diagonal BD and locate centers of gravity G1, G2 of triangles BCD and ABD.
iii. The point of intersection of lines G1G2 and G3G4 gives the center of gravity of the quadrilateral ABCD.
iv. Similarly draw the diagonal AC and determine the centers of gravity G3, G4 of triangles ABC and ADC.
a) i, ii, iii, iv
b) ii, iv, i, iii
c) iii, iv, i, ii
d) iv, i, ii, iii

Explanation: Given is irregular quadrilateral so first we have to make it to regular simpler shapes like triangle and the finding center of gravity for those and intersection of forces acting gives the center of gravity of whole.
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4. Given steps in procedure to find the center of gravity of the trapezium ABCD. Arrange the steps.
i. Join E and F which intersects the line PQ at G. G is center of gravity.
ii. Similarly produce CD to a point F so that FD=AB.
iii. Draw a line joining the midpoints P and Q of the parallel sides AB and DC respectively.
iv. Produce AB to a point E so that BE=DC.
a) i, ii, iii, iv
b) ii, iv, i, iii
c) iii, iv, ii, i
d) iii, i, ii, iv

Explanation: Given is trapezium and the steps given are for finding the center of gravity in simple way. In this the parallel lines are extended up to the length of their opposite sides and intersection of line joining ends and line joining midpoints of parallel lines gives the center of gravity.

5. The center of gravity of an equilateral triangle is on its circum center.
a) True
b) False

Explanation: For equilateral triangle the centroid and circum center and in center coincides so as the centre of gravity is the centroid for any triangle but here comes center of gravity also coincides with all other 3 points.

6. The center of gravity of a circular ring will be a ______________
a) line which acts as axis of that ring
b) point anywhere in its inner circumference
c) point at center of ring
d) point on centroid of cross section of ring

Explanation: The center of gravity is defined as point on which whole weight if body balances (or) a point through which the resultant of forces of gravity of every particle in body acts. It is also called center of mass. It may not necessarily lie within the body.

7. For symmetrical objects the center of gravity lies at intersection of axes.
a) True
b) False

Explanation: The center of gravity is defined as point on which whole weight if body balances (or) a point through which the resultant of forces of gravity of every particle in body acts. It may not necessarily lie within the body.

8. The center of gravity of a right angled triangle having h as height and b as base length and vertex at 90 degrees is at origin.
a) (h/3,b/3)
b) (b/4,h/4)
c) (b/3,h/3)
d) (h/2,b/2)

Explanation: Given is a right angled triangle having h as height and b as base length and vertex at 90 degrees is at origin. The center of gravity coincides with the centroid of the triangle the given answer is the centroid for such a triangle.

9. Which of the following game make use of center of gravity?
a) Caroms
b) Seesaw
c) Tic-Tac-Toe
d) Swing

Explanation: The center of gravity is defined as point on which whole weight if body balances (or) a point through which the resultant of forces of gravity of every particle in body acts. It is also called center of mass.

10. The center of gravity of a rectangle having h as height and w as width, one of its vertex is origin and its width is along x-axis is _____________
a) (w/3,h/3)
b) (w/4,h/4)
c) (h/2,w/2)
d) (w/2,h/2)

Explanation: Given a rectangle having h as height and w as width, one of its vertices is the origin and its width is along x-axis which is a symmetric planar object and for symmetrical objects the center of gravity lies at the intersection of axes.

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