Some Mechanical Properties of Matter Physics - Some Mechanical Properties of Matter

The contact angle between as solid and a liquid is a property of:

1. The material of the solid.
2. The material of the liquid.
3. The shape of the solid.
4. The mass of the solid.

If more air is pushed in a soap bubble, the pressure in it:

1. Decreases.
2. Increases.
3. Remains same.
4. Becomes zero.

If two soap bubbles of different radii are connected by a tube:

1. Air flows from bigger bubble to the smaller bubble till the sizes become equal.
2. Air flows from bigger bubble to the smaller bubble till the sizes are interchanged.
3. Air flows from the smaller bubble to the bigger.
4. There lis no flow of air.

A capillary tube of radius 0.50mm is dipped vertically in a pot of water. Find the difference between the pressure of the water in the tube 5.0cm below the surface and the atmospheric pressure. Surface tension of water = 0.075N/m.

A vertical metal cylinder of radius 2cm and length 2m is fixed at the lower end and a load of 100kg is put on it. Find

1. The stress.
2. The strain and.
3. The compression of the cylinder. Young's modulus of the metal = 2 × 10¹¹ N/m².

A steel plate of face area 4cm² and thickness 0.5cm is fixed rigidly at the lower surface. A tangential force of 10N is applied on the upper surface. Find the lateral displacement of the upper surface with respect to the lower surface. Rigidity modulus of steel = 8.4 × 10¹⁰N/m².

When the skeleton of an elephant and the skeleton of a mouse are prepared in the same size, the bones of the elephant are shown thicker than those of the mouse. Explain why the bones of an elephant are thicker than proportionate. The bones are expected to withstand the stress due to the weight of the animal.

A 5.0cm long straight piece of thread is kept on the surface of water. Find the force with which the surface on one side of the thread pulls it. Surface tension of water = 0.076N/m.

Estimate the speed of vertically falling raindrops from the following data. Radius of the drops = 0.02cm, viscosity of air = 1.8 × 10^-4 poise, g = 9.9m/s² and density of water = 1000kg/m³.

Consider an ice cube of edge 1.0cm kept in a gravity free hall. Find the surface area of the water when the ice melts. Neglect the difference in densities of ice and water.

The contact angle between pure water and pure silver is 90^º. If a capillary tube made of silver is dipped at one end in pure water, will the water rise in the capillary?

The yield point of a typical solid is about 1%. Suppose you are lying horizontally and two persons are pulling your hands and two person are pulling your legs along your own length. How much will be the increase in your length if the strain is 1%? Do you think your yield point is 1% or, much less than that?

A load of 10kg is suspended by a metal wire 3m long and having a cross-sectional area 4mm². Find.

1. The stress.
2. The strain and.
3. The elongation. Young's modulus of the metal is 2.0 × 10N¹¹N/ m².

The two wires shown in are made of the,

same material which has a breaking stress of 8 × 10⁸N/m². The area of cross-section of the upper wire is 0.006cm² and that of the lower wire is 0.003cm². The mass m₁ = 10kg, m₂ = 20kg and the hanger is light:

1. Find the maximum load that can be put on the hanger without breaking a wire. Which wire will break first if the load is increased?
2. Repeat the above part if m₁ = 10kg and m₂ = 36kg.

Estimate the change in the density of water in ocean at a depth of 400m below the surface. The density of water at the surface = 1030kg/m³ and the bulk modulus of water = 2 × 10⁹N/m².

A steel wire of original length 1m and cross-sectional area 4.00mm² is clamped at the two ends so that it lies horizontally and without tension. If a load of 2.16kg is suspended from the middle point of the wire, what would be its vertical depression? Y of the steel = 2.0 × 10¹¹N/m² Take g = 10m/s².

The force of surface tension acts tangentially to the surface whereas the force due to air pressure acts perpendicularly on the surface. How is then the force due to excess pressure inside a bubble balanced by the force due to the surface tension?

If a mosquito is dipped into water and released, it is not able to fly till it is dry again. Explain.

When some wax is rubbed on a cloth, it becomes waterproof. Explain.

When a glass capillary tube is dipped at one end in water, water rises in the tube. The gravitational potential energy is thus increased. Is it a violation of conservation of energy?

A steel blade placed gently on the surface of water floats on it. If the same blade is kept well inside the water, it sinks. Explain.