Physics - Properties of Matter

Question - 1

A cabel of length l can support a maximum load of 1000 kg.  If it is reduced to one-fourth (i.e., 1/4 l), the maximum load it can now support without exceeding the elastic limit would be

• A 1000 kg
• B 4000 kg
• C 250 kg
• D insufficient data

Question - 2

DImensional formula for modulus of elasticity is

• A $MLT^{-2}$
• B $MLT^{2}T^{-1}$
• C $ML^{-1}T^{-2}$
• D $ML^{2}T^{-2}$

Question - 3

A bolloon floating in air is given a slight lateral horizontal displacement.  The baloon shall now be

• A in stable equilibrium
• B in unstable equilibrium
• C in neutral equilibrium
• D oscillating

Question - 4

Young's modulus is defined as ratio of normal stress to longitudinal strain.  Hence the term 'force' refers to

• A external applied force
• B deforming force
• C restoring force
• D breaking force

Question - 5

Two steel wires have their lengths and diameters in the ratio of 1 : 2.  Their elongation for the same stretching force will be in the ratio

• A 1 : 4
• B 4 : 1
• C 1 : 2
• D 2 : 1

Question - 6

The length of a wire is increased by 1 mm on the application of a certain load.  In a wire of the same material of twice the length and half the radius of the first, the same force will produce an extension

• A 1 m
• B 2 m
• C 4 mm
• D 8 mm

Question - 7

Two rods A and B of the same material have both lengths and diameters in the ratio 2:1 respectively. They are subjected to equal torsional couples.  If $\tau _{B}$ are modulus of torsion

• A 1 : 4
• B 8 : 1
• C 1 : 8
• D 1 : 1

Question - 8

The magnitude of stress required to increase the length by 100% of a wire of young's modulus Y is

• A Y
• B Y/2
• C Y2
• D None of these

Question - 9

A vertical wire 2.0 m long and 2.0 $\times$ $10^{-6}m^{2}$ in cross-section is found to stretch 0.003 m under a load of 40 N at its lower end.  Assuming Hooke's law holds, the molecular potential energy in J of the streched wire is

• A 0.024
• B 0.048
• C 0.060
• D 0.6

Question - 10

Choose correct statement :

• A Metals have high young modulus and low elastic strain
• B Glass has young modulus and low elastic strain
• C Plastics are less stiff and do not obey Hooke's law like metals do
• D All of the above