Three forces acting on a body are shown in the figure. To have the resultant force only along the y-direction, the magnitude of the minimum additional force needed is
A uniform metal disc of radius R is taken and out of it a disc of diameter R/2 is cut-off from the end. The centre of mass of the remaining part will be
A tank is filled with water of density \[1\text{ }g/c{{m}^{3}}\] and oil of density \[0.9\text{ }g/c{{m}^{3}}\] . The height of water layer is 100 cm and of the oil layer is 400 cm. lf \[g=980\text{ }cm/{{s}^{2}}\] , then the velocity of efflux from an opening in the bottom of the tank is
A parallel plate capacitor has plates with area A and separation between it is d. A battery charges the plates to a potential difference\[{{V}_{0}}\]The battery is then disconnected and a dielectric slab of thickness d is introduced. The ratio of energy stored in the capacitor before and after the slab is introduced is
You are given n resistors, each of resistance r. They are first combined to get minimum possible resistance, then they are connected to get maximum possible resistance. The ratio between minimum to maximum resistances is
A rectangular coil of 100 turns and size \[0.1m\times 0.05\,m\] is placed perpendicular to amagnetic field of 0.1 T. The induced \[emf\] when the field drops to 0.05 T is 0.05 s is
A bomb is dropped from an aeroplane when it is at a height h directly above the target. If the aero plane is moving horizontally at a speed v, the distance by which bomb will miss the target is given by
A block B is pushed momentarily along a horizontal surface with an initial velocity \[v\]. If \[\mu \] is the coefficient of sliding friction between B and the surface, block B will come to rest after a time
A machine which is 80% efficient, uses 20 J of energy in lifting up a 2 kg mass through a certain distance. The mass is then allowed to fall through that distance. The velocity at the end of its fall is
A cylinder of height h is placed on an inclined plane, the angle of inclination of which is slowly increased. It begins to slip when the angle of inclination is \[45{}^\circ \]. What is the radius of the cylinder?
A person feels 2.5% difference of frequency of a motorcar horn. If the motorcar is moving to the person and the velocity of sound is 320 m/s, then the velocity of car will be
Two concentric spheres of radii R and r have similar charges with same surface charge densities\[(\sigma )\]. What is the electric potential at their common centre?
A transformer is used to step-up an transformation \[emf\] of 220 V to 4.4 kV in order to transmit 6.6 kV of power. If the primary coil has 100 turns, what is the number of turns in the secondary?
A body is projected vertically upwards. If \[{{t}_{1}}\] and \[{{t}_{2}}\] be the instants at which it is at a height h above the point of projection, while ascending and descending respectively, then
A particle of mass 4m at rest explodes into three fragments. Two of the fragments each of mass m move with speed v at right angles to each other. The kinetic energy released in the process is
A chord is used to lower vertically a block of mass M a distance d at a constant downward acceleration of \[\frac{g}{4}\]. Then, the work done by the chord on the block is
A bar of mass \[m\] length \[l\] is in pure translator motion with its centre of mass velocity \[v\]. It collides with and sticks to another identical bar at rest as shown in figure. Assuming that after collision it becomes one composite bar of length \[2l\], the angular velocity of the composite bar will be
An U tube of uniform bore of cross-sectional area A is set up vertically with open ends up. A liquid of mass M and density d is poured into it. The liquid column will oscillate with a period
In a ball, a person receives direct sound waves from a source 120 m away. He also receives wave from the same source which reach him after being reflected from one 25 m high ceiling at a point half-way between them. The two waves interfere constructively for wavelengths (in metre) of
A dip circle lying initially in the magnetic meridian is rotated through angle \[\theta \] is the horizontal plane. The tangent of angle of dip is increased in the ratio
A rectangular coil of single turn, having area A, rotates in a uniform magnetic field B with an angular velocity \[\omega \]about an axis perpendicular to the field. If initially the plane of the coil is perpendicular to the field, then the average induced \[emf\] when it has rotated through \[90{}^\circ \]. is
A 60 W bulb is placed at a distance of 4 m from you. The bulb is emitting light of wavelength 600 nm uniformly in all directions. In 0.1 s, how many photons enter your eye if the pupil of the eye is having a diameter of 2 mm? [Take, he =1240 eV-nm]
Two identical non-relativistic particles A and 6 move at right angles to each other, possessing de-Broglie wavelengths \[{{\lambda }_{1}}\] and \[{{\lambda }_{2}}\] respectively. The de-Broglie wavelength of each particle in their C frame of reference is
When the voltage applied to an X-rays tube increases from \[{{V}_{1}}=10kV\]to \[{{V}_{2}}=20\,kV\], the wavelength interval between \[{{K}_{\alpha }}\] line and cut-off wavelength of continuous spectrum increases by a factor of 3. Atomic number of the metallic target is
The binding energy of an electron in the ground state of He-atom is equal to \[{{E}_{0}}=24.6\,eV\].The energy required to remove both the electrons from the atom is
A photosensitive material is at 9 m to the left of the origin and the source of light is at 7 m to the right of the origin along \[x\]-axis. The photosensitive material and the source of light start from rest and moves with 8i m/s and 4i m/s respectively. The ratio of intensity at \[t=0\] to\[t=3\]s as received by the photosensitive material is
Hydrogen atoms in a sample are excited to \[n=5\] states and it is found that photons of all possible wavelengths are present in emission spectra. The minimum number of hydrogen atoms in the sample would be
A parallel beam of light of intensity \[l\] and frequency\[v\]is incident on a solid sphere of radius R as shown in the figure For this situation mark out the correct statement.
A)
The force exerted by light on the sphere is the greatest when surface of sphere is perfectly reflecting and is equal to \[\frac{2l\times \pi {{R}^{2}}}{c}\]
doneclear
B)
The force exerted by light on the sphere is independent of the nature of surface, i.e.. it is same for perfect reflector, perfect absorber, and is partially reflecting and for all it is equal to \[\frac{l\times \pi {{R}^{2}}}{c}\].
doneclear
C)
The force exerted by light on sphere is least when surface of the sphere a is perfect absorber, and is equal to \[\frac{l\times \pi {{R}^{2}}}{c}\].
A gaseous substance \[A{{B}_{2}}(g)\] converts to \[AB\,(g)\] in the presence of solid \[A(s)\] as \[A{{B}_{2}}(g)+A(s)\,\,AB(g)\] The initial pressure and equilibrium pressure are 0.7 and 0.95 bar. Now the equilibrium mixture is expanded reversibly and isothermally till the gas pressure falls to 0.4 bar. The volume percentage of \[AB(g)\] the final equilibrium is
A open manometer attached to a flask containing ammonia gas have no difference in mercury level initially as shown in fig. After sparking into the flask, ammonia is partially dissociated as \[2N{{H}_{3}}\,(g)\,\xrightarrow{\,}\,{{N}_{2}}\,(g)\,+3{{H}_{2}}\,(g)\]. Now it have difference of 18cm in mercury level into columns, what is partial pressure of \[{{H}_{2}}(g)\] at equilibrium?
An inorganic red colored compound [A] on heating gives a compound [B] and a gas [C].[A] on treatment with cone. \[HN{{O}_{3}}\]gives compound [D]. brown colour substance [E] and neutral oxide [F]. Compound [D] on warming gives off again gas [C]. Then [E] will be
At what temperature will the translational kinetic energy of H-atom equal to that for H-atom of first line Lyman transition? (Given \[{{N}_{A}}=6\times {{10}^{23}}\])
At \[25{}^\circ C\] the vapour pressure of pure liquid A (mol. wt. = 40) is 100 torr and that of pure liquid B (mol. wt. =80) is 60 torr. Find the vapour pressure of solution at \[25{}^\circ C\] if the mole ratio of A and B in vapour phase is 2 : 3.
A metal complex of coordination number six having three different types of ligands a, band c of composition \[M{{a}_{2}}{{b}_{2}}{{c}_{2}}\] can exist in several geometrical isomeric forms; the total number of such isomer is
(I) \[C{{H}_{3}}-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{2}}-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}\]
(II) \[{{C}_{6}}{{H}_{5}}-C{{H}_{2}}-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}\]
(III) \[C{{H}_{3}}-CHO\]
(IV) \[{{C}_{6}}{{H}_{5}}-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}\]
Oxygen atoms forms fee unit cell with 'A' atoms occupying all tetrahedral voids and 'B' atoms occupying all octahedral voids. If atoms are removed from two of the body diagonals then determine the formula of resultant compound formed.
To 100 mL of 0.1 M solution of sodium dihydrogen phosphate 75 mL of 0.1 M sodium phosphate is added. Calculate the pH when 25 mL of 0.1 M HCI is added to the above solution (stepwise acid dissociation constant for phosphoric acid are \[{{10}^{-3}},\,\,{{10}^{-6}}\] and \[{{10}^{-13}}\])
\[\sum\limits_{i=1}^{n}{{{a}_{i}}=0,}\] where \[|{{a}_{i}}|\,=1,\,\,\forall \,i,\] then the value of \[\sum\limits_{1\le i\le }{\,\sum\limits_{j<n}{{{a}_{i}}\cdot {{a}_{j}}}}\] is
If \[{{\sin }^{2}}\,x+{{\cos }^{2}}\,y=2\,\,{{\sec }^{2}}\,z,\] then values of and \[x,\,\,y\]and\[z\]are respectively (where, \[m,\,\,n,\,r\,\,\in l)\]
If \[\alpha ,\,\,\beta \] and \[\gamma \] are the altitudes of the \[\Delta ABC\] from the vertices A, B and C respectively, then value of \[4{{\Delta }^{2}}\,\left( \frac{1}{{{\alpha }^{2}}}+\frac{1}{{{\beta }^{2}}}+\frac{1}{{{\gamma }^{2}}} \right)\] is
The minimum value of \[|{{z}_{1}}-{{z}_{2}}|\] and \[{{z}_{1}}\]and\[{{z}_{2}}\] vary over the curve \[|\sqrt{3}\,(1-2z)\,+2i\,|\,=2\sqrt{7}\] and \[|\sqrt{3}\,(-1-z)\,-2i\,|\,=\,|\,\,\sqrt{3}\,(9-z)+18i\,\,|,\] respectively.
There are 10 girls and 8 boys in a classroom including Mr Ravi, Ms Rani and Ms Radha. A list of speakers consisting of 8 girls and 6 boys has to be prepared Mr Ravi refuses to speak. If Mr Ravi refuses to speak, if Ms Rani is a speaker. The number of ways the list can be prepared is
Let\[(0,\,1)\to \,(0,1)\]be a differential function such that \[f'(x)\ne 0\] for all \[x\,\in (0,\,\,1)\]and \[f\,\left( \frac{1}{2} \right)=\frac{\sqrt{3}}{2}\]. Suppose for all \[x\],
The set of all \[2\times 2\] matrices which commute with the matrix with respect to matrix\[\left[ \begin{matrix} 1 & 1 \\ 1 & 0 \\ \end{matrix} \right]\]multiplication is
A)
\[\left\{ \left[ \begin{matrix} a & b \\ c & a-b \\ \end{matrix} \right];\,\,a,\,\,b,\,\,c\,\,\in \,R \right\}\]
doneclear
B)
\[\left\{ \left[ \begin{matrix} a & b \\ b & c \\ \end{matrix} \right];\,\,a,\,\,b,\,\,c\,\,\in \,R \right\}\]
doneclear
C)
\[\left\{ \left[ \begin{matrix} a-b & b \\ b & c \\ \end{matrix} \right];\,\,a,\,\,b,\,\,c\,\,\in \,R \right\}\]
doneclear
D)
\[\left\{ \left[ \begin{matrix} a & b \\ b & a-b \\ \end{matrix} \right];\,\,a,\,\,b\,\,\in \,R \right\}\]
Let, a be a non-zero real number and a, p be the roots of the equation \[a{{x}^{2}}+5x+2=0\].Then, the absolute value of the difference of the roots of the equation\[{{a}^{3}}{{(x+5)}^{2}}-25a(x+5)+50=0\]
Suppose an ellipse and a hyperbola have the same pair of foci on the x-axis with centers at the origin and that they intersect at (2, 2). If the eccentricity of the ellipse is \[\frac{1}{2},\] then the eccentricity of the hyperbola is
The equation of the circle which cuts each of the three circles \[{{x}^{2}}+{{y}^{2}}=4,\]\[{{(x-1)}^{2}}+{{y}^{2}}=4\] and \[{{x}^{2}}+{{(y-2)}^{2}}=4\] orthogonally is
The number of solutions of the equation \[{{\cos }^{2}}\,\left( x+\frac{\pi }{6} \right)+{{\cos }^{2}}x-2\cos \,\left( x+\frac{\pi }{6} \right)\cos \,\frac{\pi }{6}={{\sin }^{2}}\frac{\pi }{6}\]
Direction: Let a, b and c are three non-coplanar vectors, i.e., \[[a\,b\,c]\,\ne 0\]. The three new vectors \[a',\,\,b'\] and c' defined by the equation \[a'=\frac{b\times c}{[a\,\,b\,\,c]},\,\,b'=\frac{c\times a}{[a\,\,b\,\,c]}\]and\[c'=\frac{a\times b}{[a\,\,b\,\,c]}\] are called reciprocal system to the vectors a, b and c.
If a, b, c and a', b', c' are reciprocal system of vectors, then the value of\[a\times a'+b\times b'+c\times c'\] is
Direction: Let a, b and c are three non-coplanar vectors, i.e., \[[a\,b\,c]\,\ne 0\]. The three new vectors \[a',\,\,b'\] and c' defined by the equation \[a'=\frac{b\times c}{[a\,\,b\,\,c]},\,\,b'=\frac{c\times a}{[a\,\,b\,\,c]}\]and\[c'=\frac{a\times b}{[a\,\,b\,\,c]}\] are called reciprocal system to the vectors a, b and c.
The reciprocal set of the vectors \[2i+3j-k,\]\[i-j-2k\] and \[-i+2j+2k\] are