Forces are called coplanar when all of them acting on body lie in

The system of forces acting on the aircraft are propulsive forces, aerodynamic forces, gravitational forces and these result in inertial forces.

A

True

B

False

Coplanar non-concurrent forces are those forces which __________ at one point, but their lines of action lie on the same plane.

A

Meet

B

Do not meet

C

Either ‘A’ or ‘B’

D

None of these

The below figure shows the three coplanar forces P, Q and R acting at a point O. If these forces are in equilibrium, then

A

$$\frac{{\text{P}}}{{\sin \beta }} = \frac{{\text{Q}}}{{\sin \alpha }} = \frac{{\text{R}}}{{\sin \gamma }}$$

B

$$\frac{{\text{P}}}{{\sin \alpha }} = \frac{{\text{Q}}}{{\sin \beta }} = \frac{{\text{R}}}{{\sin \gamma }}$$

C

$$\frac{{\text{P}}}{{\sin \gamma }} = \frac{{\text{Q}}}{{\sin \alpha }} = \frac{{\text{R}}}{{\sin \beta }}$$

D

$$\frac{{\text{P}}}{{\sin \alpha }} = \frac{{\text{Q}}}{{\sin \gamma }} = \frac{{\text{R}}}{{\sin \beta }}$$

The below figure shows the three coplanar forces P, Q and R acting at a point O. If these forces are in equilibrium, then
Engineering Mechanics mcq question image

Engineering Mechanics mcq question image

A

$$\frac{{\text{P}}}{{\sin \beta }} = \frac{{\text{Q}}}{{\sin \alpha }} = \frac{{\text{R}}}{{\sin \gamma }}$$

B

$$\frac{{\text{P}}}{{\sin \alpha }} = \frac{{\text{Q}}}{{\sin \beta }} = \frac{{\text{R}}}{{\sin \gamma }}$$

C

$$\frac{{\text{P}}}{{\sin \gamma }} = \frac{{\text{Q}}}{{\sin \alpha }} = \frac{{\text{R}}}{{\sin \beta }}$$

D

$$\frac{{\text{P}}}{{\sin \alpha }} = \frac{{\text{Q}}}{{\sin \gamma }} = \frac{{\text{R}}}{{\sin \beta }}$$

The change in length due to a tensile or compressive force acting on a body is given by (where P = Tensile or compressive force acting on the body, $$l$$ = Original length of the body, A = Cross-sectional area of the body and E = Young's modulus for the material of the body)

A

$$\frac{{{\text{P}}l{\text{A}}}}{{\text{E}}}$$

B

$$\frac{{{\text{P}}l}}{{{\text{AE}}}}$$

C

$$\frac{{\text{E}}}{{{\text{P}}l{\text{A}}}}$$

D

$$\frac{{{\text{AE}}}}{{{\text{P}}l}}$$

Which of the following types of inter molecular interactions or forces is/are called van der Waals forces? 1. London forces 2. Dipole - dipole forces 3. Dipole - induced dipole forces 4. Hydrogen bonding Choose the correct code:

A

Only 2, 3 and 4

B

Only 1, 2 and 3

C

Only 3 and 4

D

Only 1 and 2

A system of coplanar forces acting on a rigid body can be reduced to

A

One force only

B

One couple only

C

One force and one couple only

D

None of the above

Three forces which act on a rigid body to keep it in equilibrium. The forces must be coplanar and

A

Concurrent

B

Parallel

C

Concurrent parallel

D

None of these

In a group of 50 students who either want to join defence forces or paramilitary forces, out of which 40 students want to join defence forces and 30 want to join paramilitary forces. Find the number of students who want to join only defence forces.

A

15

B

20

C

12

D

10

E

None of these

When two equal forces are acting on a body and in the opposite direction, the force acting on the body becomes . . . . . . . .

A

two times

B

zero

C

four times

D

three times

Forces are called coplanar when all of them acting on body lie in

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