This set of Strength of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Center of Gravity”.

1. The point through which the whole weight of the body acts is called _____________

a) Inertial point

b) Center of gravity

c) Centroid

d) Central point

View Answer

Explanation: The centre of gravity of a body is the point through which the whole weight of the body acts. A body’s center of gravity is the point around which the resultant torque due to gravity forces vanishes. Where a gravity field can be considered to be uniform and the centre of gravity will be the same.

2. The point at which the total area of a plane figure is asssumed to be concentrated is called ____________

a) Centroid

b) Centre of gravity

c) Central point

d) Inertial point

View Answer

Explanation: The centroid is the point at which the total area of a plane figure is assumed to be concentrated. The centroid and centre of gravity are at the same point.

3. Where will be the centre of gravity of a uniform rod lies?

a) At its end

b) At its middle point

c) At its centre of its cross sectional area

d) Depends upon its material

View Answer

Explanation: The centre of gravity of a uniform rod lies at its middle point. The whole weight of the rod acts through its middle point.

4. Where the center of gravity of a circle lies?

a) At its centre

b) Anywhere on its radius

c) Anywhere on its circumference

d) Anywhere on its diameter

View Answer

Explanation: The whole weight of a circle can be assumed to act through its center. So the center of gravity of a circle is at its center.

5. Where will be the center of gravity of the following section will lie In coordinates?

a) (6,3)

b) (6,6)

c) (6,1.5)

d) (1.5,3)

View Answer

Explanation: The centre of gravity of this rectangular area will be half of 3cm from x-axis and half of 12 from the y-axis. therefore the center of gravity will be at (6,1.5).

6. Where will be the centre of gravity of the T section shown in the figure?

a) At 8.545cm

b) At 6.5cm

c) At 5cm

d) At 9.25cm

View Answer

Explanation: The center of gravity is given by, y = (a

_{1}y

_{1}+ a

_{2}y

_{2}) / (a

_{1}+ a

_{2}) = ( 36×11.5 + 30×5) / (36+30) = 8.545cm.

7. Where will be the center of gravity of the L-section shown in the figure?

a) (1.28,2.64)

b) (1.45,3.24)

c) (1.64,3.28)

d) (2.24,3.68)

View Answer

Explanation: The center of gravity is given by, y = (a

_{1}y

_{1}+ a

_{2}y

_{2}) / (a

_{1}+ a

_{2}) = (10×3.5 + 4×0.5) / (10+4) = 2.64cm.

This will on for the y-axis.

For the x-axis, The center of gravity is given by, x = (a

_{1}x

_{1}+ a

_{2}x

_{2}) / (a

_{1}+ a

_{2}) = (0x1 + 4×2) / (10+4) = 1.28cm.

So the center of gravity will be at (2.33, 4.33).

8. Where will be the center of gravity of the figure shown ?

a) (3.45,4.52)

b) (3.59,7.42)

c) (3.66,8.84)

d) (3.88,8.88)

View Answer

Explanation: Area of triangle = 50, area of rectangle = 100

The center of gravity is given by, y = (a

_{1}y

_{1}+ a

_{2}y

_{2}) / (a

_{1}+ a

_{2}) = (50×20/3 + 100×10) / (50+100) = 8.88cm.

This will on for the y-axis.

For the x-axis, The center of gravity is given by, x = (a

_{1}x

_{1}+ a

_{2}x

_{2}) / (a

_{1}+ a

_{2}) = (50×6.66 + 100×2.5) / (50+100) = 3.88cm.

So the center of gravity will be at (2.33, 4.33).

9. Where will be the center of gravity of an I section will be if the dimension of upper web is 2x10cm, lower web is 2×20 and that of flange is 2x15cm If the y-axis will pass through the center of the section?

a) 7.611cm

b) 9.51cm

c) 9.31cm

d) 11.5cm

View Answer

Explanation: The center of gravity is given by, y = (a

_{1}y

_{1}+ a

_{2}y

_{2}+ a

_{3}y

_{3}) / (a

_{1}+ a

_{2}+ a

_{3}) = (20×18 + 30×9.5 + 40×1 / (20 +30+40) = 7.611cm.

**Sanfoundry Global Education & Learning Series – Strength of Materials. **

To practice all areas of Strength of Materials, __here is complete set of 1000+ Multiple Choice Questions and Answers__.

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