Engineering Mechanics Practice Test 7

1. When we apply the equilibrium equations in the free body diagram of the screw, for two force members to be in equilibrium then _________

They must be in the same direction

They must be of different magnitude

They must be in the opposite direction cancelling each other

They both must not be collinear

2. The normal force exerted by the surface of the wedge is normal to the surface of the ________

Base of the body residing over it

Base of the wedge

Earth’s surface

Base of the body just neighbour to the wedge

3. In rolling, there is the involvement of the vector math. So for rolling which of the following is correct? (For A representing the vector representation of the axis of rotation, r the radius vector and F the force vector)

Ax(rxF)

A.(rxF)

Fx(r.F)

A.(r.F)

4. For the rolling of the body right handed coordinate system means (consider the mentioned axis to be positive)?

Thumb is z-axis, fingers curled from y-axis to x-axis

Thumb is z-axis, fingers curled from x-axis to y-axis

Thumb is y-axis, fingers curled from x-axis to z-axis

Thumb is x-axis, fingers curled from z-axis to y-axis

5. What does the moment of the force measured in the rolling of the body?

The total work done on the body by the force

The tendency of rotation of the body along any axis

The moment of inertia of the body about any axis

The couple moment produce by the single force acting on the body

6. What is j.j?

∞

-1

7. In the free body diagrams involving the wedges we have use of vector math, so for two vectors A and B, what is A.B (if they have angle α between them)?

√(|A||B|) cosα

|A||B| cosα

|A||B| sinα

|A||B|

8. At what conditions does the Coulomb friction occur between the surfaces in contact of journal bearing?

When there is no lubricating fluid

When there is no friction fluid

When there is no cohesive fluid

When there is no adhesive fluid

9. In the equation Wa/r generally used in the rolling frictional calculations, what does each stands for?

P is the force, W is weight of the body, r radius and a coefficient of rolling friction all in normal powers

P is the force, W is weight of the body in kg, r radius and a coefficient of rolling friction

P is the force in nano Newton, W is weight of the body, r radius and a coefficient of rolling friction

P is the force, W is weight of the body, r radius cm and a coefficient of rolling friction

10. The frictional force is directly proportional to the surface of the solid.

True

False