Mechanical Engineering - Online Test

Q1. Let .  Consider the set ܵ of all vectors   such that a2 + b2 = 1 where  Then ܵ is
Answer : Option C
Explaination / Solution:



Q2. The spring constant of a helical compression spring DOES NOT depend on
Answer : Option B
Explaination / Solution:

The spring constant (k) for the compression helical spring is given by,

So, K is dependent on wire diameter, number of active coils, modulus of rigidity, coil diameter, but does not depends on the martial strength. 

Q3. The figure below represents a triangle PQR with initial coordinates of the vertices as P(1,3),Q(4,5) and R(5,3.5). The triangle is rotated in the X-Y plane about the vertex P by angle θ in clockwise direction. If sinθ= 0.6 and cosθ= 0.8, the new coordinates of the vertex 𝑄 are

Answer : Option A
Explaination / Solution:


Since the triangle is rotated in CW direction, hence, for the new point Q’ (x,y),
x > 4 and y < 5 __________(1)
and PQ = PQ’ or QR = Q’R’ 

Now we can get the answer easily by checking the option

Q4.
A hole is specified as  The mating shaft has a clearance fit with minimum clearance of 0.01 mm. The tolerance on the shaft is 0.04 mm. The maximum clearance in mm between the hole and the shaft is
Answer : Option C
Explaination / Solution:



Q5.
Let the probability density function of a random variable, X, be given as:

where u(x) is the unit step function.
Then the value of 'a' and Prob {X ≤ 0}, respectively, are
Answer : Option A
Explaination / Solution:




Q6. A two-member truss PQR is supporting a load W. The axial forces in members PQ and QR are respectively

Answer : Option B
Explaination / Solution:

FBD for the point Q is given by, 


Q7. In order to have maximum power from a Pelton turbine, the bucket speed must be
Answer : Option B
Explaination / Solution:

Explanation: Since, velocity of bucket = ½ times the velocity of jet.

Q8. In orthogonal turning of low carbon steel pipe with principal cutting edge angle of 90o, the main cutting force is 1000 N and the feed force is 800 N. The shear angle is 25o and orthogonal rake angle is zero. Employing Merchant’s theory, the ratio of friction force to normal force acting on the cutting tool is
Answer : Option C
Explaination / Solution:



Q9. For a complex number z,  is
Answer : Option D
Explaination / Solution:



Q10. In the gear train shown, gear 3 is carried on arm 5. Gear 3 meshes with gear 2 and gear 4. The number of teeth on gear 2, 3, and 4 are 60, 20, and 100, respectively. If gear 2 is fixed and gear 4 rotates with an angular velocity of 100 rpm in the counter clockwise direction, the angular speed of arm 5 (in rpm) is 

Answer : Option C
Explaination / Solution:

Given (taking CW as positive)