Questions
1
In a squared and ground helical spring the effective number of turns is increased by
Answer: 2
2
Frequency of the fluctuating load on a helical compression spring should be
Answer: twenty times the natural frequency of vibration
3
Two concentric springs with stiffness equal to 100 N/mm and 80 N/mm respectively, when subjected to a load of 900 N will deflect by
Answer: 5 mm
4
Stiffness of the spring can be increased by
Answer: decreasing the number of turns
5
The stress induced in an extra full length leaf in case of a prestresed leaf spring is
Answer: equal to that in graduated leaves
6
Initial gap between two turns of a close coiled helical tension spring should be
Answer: 0
7
Due to addition of extra full length leaves the deflection of a semi-elliptic spring
Answer: decreases
8
A connecting rod of mass 5.5 kg is placed on a horizontal platform whose mass is 1.5 kg. It is suspended by three equal wires, each 1.25 m long, from a rigid support. The wires are equally spaced round the circumference of a circle of 125 mm radius. When the c.g. of the connecting rod coincides with the axis of the circle, the platform makes 10 angular oscillations in 30 seconds. Determine the mass moment of inertia about an axis through its c.g.
Answer: 0.198 kg-m2
9
In order to find the radius of gyration of a car, it is suspended with its axis vertical from three parallel wires 2.5 metres long. The wires are attached to the rim at points spaced 120° apart and at equal distances 250 mm from the axis. It is found that the wheel makes 50 torsional oscillations of small amplitude about its axis in 170 seconds. Find the radius of gyration of the wheel.
Answer: 268 mm
10
A small connecting rod of mass 1.5 kg is suspended in a horizontal plane by two wires 1.25 m long. The wires are attached to the rod at points 120 mm on either side of the centre of gravity. If the rod makes 20 oscillations in 40 seconds, find the radius of gyration of the rod about a vertical axis through the centre of gravity.
Answer: 107 mm
