Properties of matter Questions and Answers

22 A wire of length is stretched by a force F to cause an extension x Another wire of same material and same volume but 50 larger in length than the first wire the force required for the same extension will be 3 1 OF 16 3 F 4 2 4 3 615 F 22 3 z t 31 SE 1 3

1 Assertion A The drift velocity of electrons in a metallic conductor decreases with rise of temperature of conductor Reason R On increasing temperature the collision of electrons with lattice ions increases this hinders the drift of electrons

Two point masses of mass m and 2m placed on smooth horizontal plane are connected by a light rod of length Masses are given velocities in horizontal plane perpendicular to rod as shown If area of cross section of rod is A and Young s modulus is Y then elongation in the rod will be A B C D mv AY 2mv AY 6mv AY 3mv AY m Vo 200 2m

How come certain solid objects are elastic a Because chemical forces are not rigid while they are flexible within limits they oppose deformations b Because physical systems under stress tend to take the shape determined by the equilibrium of their inner parts c Because their elementary parts are connected by t ny coil springs d All of the above are true e Only a and b above are true

sir could u pls explain how to solve this sum A bar of cross section A is subjected to equal and opposite tensile force F at its ends If there is a plane through the bar making an angle Q with the plane at right angles to the bar in the figure F F a Find the tensile stress at this plane in terms of F A and Q b What is the shearing stress at the plane in terms of F and Q c For what value of Q is tensile stress a maximum

9 A river 4 0 miles wide is flowing at the rate of 2 miles hr The minimum time taken by a boat to cross the river with a speed v 4 miles hr in still water is approximately 1 1 hr and 0 minute 2 2 hr and 7 minutes 3 1 hr and 12 minutes 4 2 hr and 25 minutes

Water from a pipe is coming at a rate of 100 liters per minute If the radius of the pipe is 5 cm the Reynolds number for the flow is of the order of density of water 1000 kg m coefficient of viscosity of water 1 mPa s 1 10 2 104 3 10 4 106

A stone weighs 750 N in air and has an apparent weight of 250 N in water The buoyant force experienced by the stone is Select one O a 100 N b 250 N c 500 N

A V tube of uniform cross sectional area A is filled with a liquid of density p as shown in figure Each arm has length 1 and inclined to vertical at an angle a If the free surface of the liquid in one arm is disturbed by displacing it a depth x below the equilibrium configuration determine the frequency of oscillation a A c 2 1 1 2 g cos a A 1 g cosa X X b a 1 2 V d 2 B B g cos a 1 sa g cos c

The length of a metal wire is when the tension in it is F and when the tension becomes F Find the natural length of wire L F F 2 2 a F F c L F F F F b d 4 F F F F 21 G F C F F F

26 A uniform wire of mass M length L area of cross section A and Young s modulus Y is suspende from the ceiling Elongation of the wire due to its own weight is 1 3 MgL 2AY MgL 2V 2 4 MgL 2AY MgL3 2AY

A squirrel of mass m climbs slowly on a thin straight vertical rod of length L Mass of the rod is negligible as compared to that of the squirrel and size of the squirrel is negligible as compared to the length I that it climbs on the rod Due to weight of the squirrel the rod bends at its lower end through an angle and due to elasticity of the material of the rod a restoring torque CO is developed If C 2mgl find the maximum length the squirrel can climb on the rod a L 2 c L b 3L 4 d 2L

11 A potentiometer consists of a wire of length 4 m and resistance 20 S2 If it is connected to a cell of emf 20 volt the potential difference per unit length of the wire will be b 2 Vm 1 a 0 5 V m 1 c 5 Vm 1 d 1 0 V m 1

24 A liquid flows out drop by drop from a vessel through a vertical tube with an internal diameter of 2 mm then the total number of drops that flows out during 10 grams of the liquid flow out Assume that the diameter of the neck of a drop at the moment it breaks away is equal to the internal diameter of tube and surface tension is 0 02 N m

A uniform rod of length 7 cross section area A and Young s modulus Y is placed on a smooth horizontal surface Two horizontal forces 3F and 2F are applied at the ends of the rod as shown If the elastic potential energy stored in the rod is U n 19F 1 12AY Find the value of n

11 The surface tension of water is 75 dyne cm Find the mini mum vertical force required to pull a thin wire ring up refer figure if it is initially resting on a horizontal water surface The circumference of the ring is 20 cm and its weight is 0 1 N a 0 125 N b 0 225 N c 0 115 N d 0 130 N

For the metal console beam in Figure 9 replace the moment and the two forces applied by a moment equivalent and the resultant of the two forces at point A A y 1 5 m L x 500 N m 3 0 5 m 2 kN 70 1 2 kN 10 15 m 0 15 m

Deformation and Breaking of a Bone If a compressive force of 3 x 104 N is exerted on the end of 20 cm long bo area 3 6 cm Find if the bone will break and or the deformation in bone Given that the compress in 77 x 108 N m and Young s modulus of bone 1 5 1010 N m of cross sectional te

A rod of length 2m at 0 C and having expansion coefficient a 3x 2 10 C where x is the distance in cm from one end of rod The length of rod at 20 C is A 2 124 m B 3 24 m C 2 0120 m D 3 124 m

A proton and an electron are accelerated by the same potential difference Let and X denote the de Broglie wavelengths of the electron and the proton respectively O A Ap O Ap O A Ap none of these

Two wires of the same length and same area of cross section are suspended as shown Their Young s moduli are in the ratio 2 3 Blocks are in equilibrium in each arrangement wire 1 O O m wire 2 m At equilibrium strain will be in ratio 3 4 At equilibrium stress will be in ratio 2 3 When stretched and released they will oscillate with time periods in the ratio 3 2 When stretched and released they will oscillate with time periods in the ratio 3 2

The densities of wood and benzene at 0 C are 880 kg mand 900 kg m 3 respectively The coefficients of volume expansion of wood is 1 2 x 10 3 C 1 and that of benzene is 1 5 x 10 3 C 1 Value of temperature in C at which a piece of this wood would just sink in benzene at the same temperature isT Then find value of 3 x 10 T where T is tempture in C 40 20 60 80

An Air Bubble rising up inside a Liquid An air bubble of radius 1 cm rising at a steady rate of 0 5 cm s through a liquid of density 0 8 gm cm3 Calculate the coefficient of viscosity of the liquid Neglect the mass of air

Pressure Difference in a U Tube The internal radius of one arm of a U shaped capillary is 1 mm and that of oth is 2 mm One arm of tube is connected to a vacuum pump and after some time the level of mercury in both arms found to be equal If surface tension of mercury is T and density p find the difference in air pressure S in the tw

39 The surface energy of a drop is E If one thousand such drops coalesce to form a large drop then its surface energy is E The ratio is E 1 1 10 2 10 1 3 1 100 AY 1000 1

If water in a lake were to behave like other liquids then in extremely cold weather it would freeze A from top to bottom B from bottom to top C simultaneously throughout the depth D first on the surface bottom and sides and then in the interior

Calculate the linear electron density of Gallium Arsenide in which its width is 10 nm The sub band values of the GaAr are n 2 n 2 2 6 2 3 a a n b n a 2 6 a 2 3 c n a 2 3 d n C

Person property and face camera 69 A copper wire of length 3m and 1mm diameter is subjected to a tension of 5N Calculate the elongation produced if the young s modulus of copper is 120GPa 1800m 15m 15 9mm 0 125x10 3 m 3702675675

BPH2101 PHYSICS 35 The body will regain it is previous shape and size only when the deformation caused by the external forces is within a certain limit What is that REMAINING TIME HOURS MINUTES SECONDS 1 48 32 limit Propotional limit Elastic limit Plastic limit ODeformation limit

are made of materials whose coefficient of linear expansions are a1 and 2 If the difference between two lengths is independent of temperature l l2 1 2 INCORRECT

1 C 22 A wire of length area of cross section A and weight w is subjected to external force 2w If Y is Young s modulus then total extension in wire is 5wl AY 4 9F we FJ 2 5wl 2AY 5we Aztiry 2 h 201 ZAY AY 3 2 90 3 3 3 E

A suspended long metal wire is stretched a small distance x by a load W in newton suspended at the other end Select the best answer out of the following Question Type Single Correct Type 1 The loss in potential energy of the load W is equal to the gain in energy of the wire in stretching a length x 2 The energy stored in the wire can be calculated from the area between the force extension graph and the extension axis 3 Wx The energy per unit volume stored in the wire 2 ang a chau

The relation between y n and K for a elastic material is 1 1 K 3y 1 3 Y 1 1 37 3K 3K 1 9K 1 91 2 4 9n 1 Y 31 9K

4 inversely proportional to the square of the radius of sphere A sphere is dropped gently into a medium of infinite extent As the sphere falls the force acting downwards on it 1 remains constant throughout 2 increases for sometime and then becomes constant 3 decreases for sometime and then becomes zero 4 increases for sometime and then decreases If it is allowed to fall in vacuum

A steel wire is suspended vertically from a rigid support When loaded with a weight in air it expands by L and whe the weight is immersed completely in water the extension is reduced to L Then relative density of the material of th weight is L 1 2 Lw L 3 L 4 L L

1 V 25 2 5 V 3 V 5 4 25 V If work done in stretching a wire by 1mm is 2J the work necessary for stretching another wire of same material bu with double the radius and half the length by 1mm in joule is 1 1 4 2 4 3 8 4 16 50 4 6 kmx

Two wires A and B of same length and of the same material have the respective radii r and r Their one end is fixed with a rigid support and at the other end equal twisting couple is applied Then the ratio of the angle of twist at the end of A and the angle of twist at the end of B will be 2 1 2 2 H

Two wires one of steel Ysteel 2 x 1011 N m and the other of copper Ycu 10 1 N m have same length and radii If on applying a force F the length of first wire increases by l 0 then force required to increase the length of second wire by same amount is

41 Young s modulus of a wire of length 1 and radius r is Y I Length of the wire is reduced to and radius also reduced to a r Young s modulus will now be 2 Y 4 Y b 2 2 c 2Y d Y 49 n

on the radius of the spher 27 The radius of a metal sphere at room temperature T is R and the coefficient of linear expansion of the metal is a The sphere heated a little by a temperature AT so that its new temperature is T AT The increase in the volume of the sphere is approximately NCERT Exemplar a 2 R AT c 4 R AT 3 8 A cubic I b R AT d 4 R AT

In a grid iron pendulum there are 3 iron rods and 4 brass rods Length of each brass rod is 50 cm a of iron is 12 x 10 6 C and a of Brass is 18 10 6 C Length of each iron rod is A 50 cm B 100 cm C 120 cm D 60 cm

20 A wire Y 2x 10 N m has length 1 m and area 1 mm the work required to increase its length by 2 mm is b 40 J a 0 4 J c 4 J d 400 J

When a massive string mass length is hung from two supports the shape it forms is called catenary e e x ex then find out tension at lowest The equation for catenary shown in diagram is Y 2 point A 2 ga B ga y 0 0 C ga X D 4uga

A ball falling in a lake of depth 200 m shows 0 01 decreas in its volume at the bottom What is the bulk modulus of th material of the ball a 19 6 108 N m b 19 6x10 N m c 19 6x10 0 N m 6x10 N m 1012 10

gas 24 At what temperature the rms velocity of molecules would be double of its value at NTP if upressure is remaining constant b 819 K a 819 C C c 546 K IMP PMI 201S d 546 C Quorage kinetic energy per mole of 1

You have just purchased a diamond ring claimed to be a pure diamond The ring weighs 20 g and displaces 8 cm on water when fulled immersed Is this a pure diamond Take the specific grvaity of diamond as 3 5 O No Yes Cannot tell

A rod of mass Mis placed over smooth horizontal surface Forces 2F F are applie at the ends of the rod as shown If length cross sectional area and Young s mod lus of rod are L A and Y respectively then total elongation of rod will be where F Mg and a are co prime integers Find value of a B L A Y Smooth 7777 2F a MgL B AY

3 10 A force of 1000 newton doubles the length of cord having cross sectional area 1 mm Th Young s modulus of the material of the cord is 1 2 x 106 N m 3 10 N m 2 5 x 105 N m 4 105 N m

b Considering the equilibrium of the water find the resultant force exerted by the sides of the glass vessel on the water Atmospheric pressure 1 0 105 N m Density of water 1000 kg m and g 10 m s a 204 N b 1 N upward

A 1000 kg lift is tied with metallic wire of maximum safe stress of 1 4 x 108 N m If the maximum acceleration of the lift is 1 2 m s 2 then the minimum diameter of the wire is g 9 8 ms 2 2 0 01 cm 4 0 02 cm 1 0 01 m 3 0 001 m