Physics 1 Marks Question

For solids with elastic modulus of rigidity, the shearing force is proportional to shear strain while for fluids it is proportional to rate of shear strain. With reference to the elastic modulus of rigidity for solids, the shearing force is proportional to the shear strain. With reference to the elastic modulus of rigidity for fluids, the shearing force is proportional to the rate of shear strain.

For a fluid in steady flow, the increases inflow speed at a constriction follows from conservation of mass while the decrease of pressure there follows from Bernoulli's principle. For a steady-flowing fluid, an increase in its flow speed at a constriction follows the conservation of mass/ Bernoulli's principle.

Viscosity of gases Increases with temperature, whereas viscosity of liquids decreases with temperature. Most fluids offer resistance to their motion. This is like internal mechanical friction, known as viscosity. Viscosity of gases increases with temperature, while viscosity of liquids decreases with temperature.

By doing so the area of outlet of water jet is reduced, so velocity of water increases according to equation of continuity, Area × Velocity = Constant.

Surface tension of liquids generally decreases with temperatures. The surface tension of a liquid is inversely proportional to temperature.

Density of air is the maximum near the sea level. Density of air decreases with increase in height from the surface. At a height of about 6km, density decreases to nearly half of its value at the sea level. Atmospheric pressure is proportional to density. Hence, at a height of 6km from the surface, it decreases to nearly half of its value at the sea level.

For the model of a plane in a wind tunnel, turbulence occurs at a Greater speed for turbulence for an actual plane (greater/ smaller). For the model of a plane in a wind tunnel, turbulence occurs at a greater speed than it does for an actual plane. This follows from Bernoulli's principle and different Reynolds' numbers are associated with the motions of the two planes.

Coefficient of viscosity n is less as compared to the value of honey. So, water flows faster than honey.

In the cotton wick, there are very large number of capillaries in which oil continues to rise.

It is a simple device which is used for measuring the velocity of the flow at any depth in a flowing liquid. It is based on Bernoulli's theorem.

This is done to reduce the backward drag of the atmosphere.

Systolic pressure.

In order to have low value of surface tension so that it can spread over large area.

When air is blown in between two balls suspended close to each other with high speed, a low pressure is created between the balls which is much less than the atmospheric pressure beyond the balls. Due to this, balls are attracted towards each other. This is according to Bernoulli's theorem.

The height of mercury in the inclined case will be 76cm.

Under normal conditions, it will be 76cm of vertical column. So, the height of mercury in the slant length has to be 76cm.

The liquid comes to rest due to the viscous force i.e., due to internal fluid friction between its different layers.

10.34m.

To compensate for excess pressure, the liquid rises.

No.

The apparent weight of the floating block is equal to zero because the weight of the block acting vertically downwards is balanced by the buoyant force acting on the block upwards.

Zero.

Surface tension of the liquid decreases.

The membrane has two surfaces. Force on frame due to surface tension = 8SL.

It is so because the pressure of water in reservoir increases with depth.

Because they have zero terminal velocity.

Due to increased velocity in the lesser cross-sectional area, the pressure will be less as there exists a streamlined flow.

Due to reduction in moment of inertia, angular velocity increases to keep the angular momentum constant.

Surface tension:

1. Reduces with increasing impurity.
2. Increases with decrease in temperature.

It will move up.

1. For a solid body of uniform density, the centre of gravity coincides with the centre of buoyancy.
2. For a solid body having different densities over different parts, its centre of gravity does not coincide with the centre of buoyancy.

Pressure increases as it is proportional to the depth we move into a liquid due to the weight of the liquid between the two layers.

This is done to increase the velocity of water flowing out of the pipe.

No, two streamlines cannot cross each other.

The pressure of air inside the bottle and the adhesive force between water and glass do not permit the water to get filled in the bottle with narrow neck.

Open tube manometer is used for measuring pressure difference.

Due to decrease in viscosity with increase of temperature.

Due to surface tension.

For equal volume, the vertical height of the liquid in the container will be more if the cross-section reduces at the top. So, pressure at the bottom of the container with less area is more.

Surface tension.

Excess pressure always acts on the concave side and for mercury there is upper convex surface. So, it drops its level in capillary tube.

When some soap is dissolved in water, the surface tension of water decreases. Thus, the less energy required to spray water.

So that small pressure is exerted while carrying them.

Temperature (T) remains constant only near the surface of the earth not at greater height.

A velocity gradient of “v/ r” is seen in the tube due to the phenomenon of viscosity.

Actually the weight of plastic bag when filled with air pressure is more than when it is empty. The increase in weight equals the buoyant force due to air, so the bag weighs the same.

Due to high velocity of air outside the house, the pressure inside becomes more than outside. So, it rises up.

It is so because the pressure of water in reservoir increases with depth.

A liquid can be in equilibrium, if:

1. Only normal forces act on it.
2. The pressure at all points in a surface remains constant.

A hot liquid moves faster than cold liquid because the viscosity of liquid decreases with the increase in temperature.

Low value of surface tension has been kept for paints and oils so that it can spread over large area.

Excess pressure is inversely proportional to the radius.

When air is blown below one pan, there will be increase in air velocity and due to which the pressure drops there. Hence, the pan goes down.

Due to surface tension, the water film formed in between the hairs that tends to make the surface area minimum. As a result of which the hairs of shaving brush come close to each other.

Systolic pressure.

The level of water in a beaker will rise: It is so because the density of water formed by melting of ice is less than the density of liquid in a beaker. Due to which the volume of the water formed by melting the ice will be more than the volume of the portion of the ice in liquid while floating in liquid.

Zero, because the body after attaining terminal velocity will continue moving with same velocity through the viscous medium.

Soap bubble bursts after some time because the pressure inside it become more than the outside pressure.

Viscosity of a gas remains unchanged with increased pressure.

The liquid will rise to the level available and form a meniscus of large value.

There are two main reasons of using mercury:

1. Very high density of mercury.
2. Negligible vapour pressure of mercury.

The critical speed of a fluid depends on (a) diameter of tube, (b) density of fluid, (c) coefficient of viscosity of the fluid.

Due to change in viscosity with temperature.

By doing so the area of outlet of water jet is reduced, so velocity of water increases according to equation of continuity, Area × Velocity = Constant.

No, it does not matter if one uses gauge instead of absolute pressures in applying Bernoulli's equation unless the atmospheric pressure at the two points where, Bernoulli's equation is applied are significantly different.

Mercury rises in the tube is for atmospheric pressure up to 76cm of vertical length. If it is tilted also, the vertical length should be same.

Surface tension.

Density of air is the maximum near the sea level. Density of air decreases with increase in height from the surface. At a height of about 6km, density decreases to nearly half of its value at the sea level. Atmospheric pressure is proportional to density. Hence, at a height of 6km from the surface, it decreases to nearly half of its value at the sea level.

Oil has low surface tension than water. So, it forms a thin layer over water.

Two streamlines can never cross each other because if they cross them at the point of intersection, there will be two possible direction of flow of fluid which is impossible for streamlines.

When the upthrust balances the weight of the body, the floating body is in equilibrium.

It depends on the area of the layer and velocity gradient in contrast to normal friction.

No, Bernoulli's equation cannot be used to describe the flow of water through a rapid in a river because Bernoulli's equation can be utilised only for streamline flow.

So, they can spread over large area easily.

When the boats come closer to each other, the air velocity between the narrow gap increases and pressure decreases. Thus the boats are further pushed towards each other.

1 : 1 as the velocity of efflux will be the same at two places-both at a depth ‘h' from the free surface and at a height 'H' from the bottom.

If the angle of contact between water and the material of the raincoat is obtuse, then rainy water does not wet the raincoat. Thus, the raincoat becomes waterproof.

1. The surface tension is increased.
2. The surface tension decreases.
3. The angle of contact decreases.

If solute is highly soluble-surface tension increases. If solute is less soluble, surface tension decreases.

Because terminal velocity of air bubble is negative.

When a piece of the wood burns, then steam formed and water appear in the form of drops due to surface tension on the other end.

Temperature of the drop remains unchanged.

Because water vapour exerts pressure. Thus, the barometric height decreases.

The addition of flux reduces the surface tension of molten tin, hence it spreads.

The viscosity of liquid decreases with the increase in temperature. Therefore, viscosity of hot liquid is less than that of cold liquid. Due to this, hot liquid moves faster than the cold liquid.

This is due to Magnus effect.

For capillary action.

The viscous force between two layers increases with the increase in relative velocity.

The pressure varies with height of liquid column. So, at a lower level (feet), the pressure is more than at the top (head).

The angle of contact of a liquid increases with the increase in temperature.