Questions
1
A copper and a steel wire of the same diameter are connected end to end. A deforming force F is applied to this composite wire which causes a total elongation of 1 cm. The two wires will have
Answer:A, D
3
A wire is suspended from the ceiling and stretched under the action of a weight F suspended from its other end. The force exerted by the ceiling on it is equal and opposite to the weight.
Answer:A, D
4
The stress-strain graphs for the two materials are shown in the figure.
Answer:C, D
5
Consider two cylindrical rods of identical dimensions, one of rubber and the other of steel. Both the rods are fixed rigidly at one end to the roof. A mass M is attached to each of the free ends at the centre of the rods.
Answer:the steel rod will elongate, without any perceptible change in shape, but the rubber rod will elongate with the shape of the bottom edge tapered to a tip at the centre
6
A spring is stretched by applying a load to its free end. The strain produced in the spring is
Answer:longitudinal and shear
7
The temperature of a wire is doubled. The Young’s modulus of elasticity
Answer:will decrease
8
The maximum load a wire can withstand without breaking when its length is reduced to half of its original length, will
Answer:remain same
10
A copper and a steel wire of the same diameter are connected end to end. A deforming force F is applied to this composite wire which causes a total elongation of 1cm. The two wires will have
Answer:A, D
11
9A rod of length l and negligible mass is suspended at its two ends by two wires of steel (wire A) and aluminium (wire B) of equal lengths (Fig. in below). The cross-sectional areas of wires A and B are 1.0 mm2 and 2.0 mm2, respectively.
(YAl 70 * 109 Nm– 2 and Ysteel 200 * 109 Nm-2
(YAl 70 * 109 Nm– 2 and Ysteel 200 * 109 Nm-2
Answer:B, D
12
The stress-strain graphs for two materials are shown in Fig. below (assume same scale)
Answer:C, D
13
A rectangular frame is to be suspended symmetrically by two strings of equal length on two supports (Fig. in below). It can be done in one of the following three ways;
The tension in the strings will be
Answer:least in (b).
14
A mild steel wire of length 2L and cross-sectional area A is stretched, well within elastic limit, horizontally between two pillars (Fig. in below). A mass m is suspended from the mid point of the wire. Strain in the wire is
Answer:x2 / 2 L2
15
A rigid bar of mass M is supported symmetrically by three wires each of length l . Those at each end are of copper and the middle one is of iron. The ratio of their diameters, if each is to have the same tension, is equal to
Answer:(b)
16
The maximum load a wire can withstand without breaking, when its length is reduced to half of its original length, will
Answer:remain same.
18
Streamline flow is more likely for liquids with
Answer:low density and high viscosity
19
The Poisson’s ratio of a material is 0.5. If a force is applied to a wire of this material, there is a decrease in the cross-sectional area by 4%. The percentage increase in the length is
Answer:4%
Chapters
- Physical World
- Units and measurements
- Motion in a straight line
- Motion in a plane
- Laws of motion
- Work energy and power
- System of particles and rotational motion
- Gravitation
- Mechanical properties of solids
- Mechanical properties of fluids
- Thermal properties of matter
- thermodynamics
- Kinetic theory
- Oscillations
- Waves
