Mechanical Engineering - Engineering Mechanics

Exercise :: Engineering Mechanics - Section 4
1.
Three forces acting on a rigid body are represented in magnitude, direction and line of action by the three sides of a triangle taken in order. The forces are equivalent to a couple whose moment is equal to

A.
area of the triangle B.
twice the area of the triangle C.
half the area of the triangle D.
none of these

Answer: Option B

Explanation:

2.
If tension in the cable supporting a lift moving downwards is half the tension when it is moving upwards, the acceleration of the lift is

Answer: Option D

Explanation:

3.
Efficiency of a screw jack is given by(where α = Helix angle, and φ = Angle of friction.)

Answer: Option B

Explanation:

4.
When a train is rounding a curve, the side thrust on the wheel flanges is prevented by raising the outer edge of the rail.

Answer: Option A

Explanation:

5.
Frequency of vibrations means the number of cycles per second.

Answer: Option A

Explanation: