A large ball 2 m in radius is made up of a rope of square cross section with edge length 4 mm. Negleting the air gaps in the balol, what is total length of the rope to the nearest order of magnitude?

If large square beds of equal size are to be made on a plot of land 18 metres long and 15 metres wide in order to plant vegetables, what is the maximum possible length of each bed ?

A solenoid of length 25 cm has inner radius of 1 cm and is made up of 250 turns of copper wire. For a current of 3A in it, What will be the magnitude of the magnetic field inside the solenoid?

A winding wire which is used to prepare a solenoid of length 80 cm can bear a maximum cuurent of 10 A. the cross-sectional radius of the solenoid is 3 cm. what should be the length of the winding wire if a magnetiic field of 0.2 T is to be produced at the centre of the solenoid along its axis?

A copper wire and a steel wire of same length and same cross-section are joined end to end. The compositive wire is hung from a rigid support and a load is suspended form the free end. The increase in length of the compositive wire is 4 mm. The increase in copper wire will be (Y_(copper)=1.2xx10^(11)N//m^(2),Y_(steel)=2xx10^(11)N//m^(2))

A bar magnet of magnetic moment 10 Am^ 2 has a cross sectional area of 2.5 xx1O^-4 m^2 .If the intensity rof magnetisation of the magnet is 10^6 Am^-1 , the length of the magnet is

A calorie is a unit of heat and it equals 4.2 J, where 1 J = kg m^2 s^-2 .. A distant civilisation employs a system of units in which the units of mass, length and time are α kg, beta m and gamma s. Also J' is their unit of energy. What will be the magnitude of calorie in their units?

A straight horizontal conducting rod of length 0.45 m and mass 60 g is suspended by two vertical wires at its ends. A current of 5.0 A is set up in the rod through the wires. What will be the total tension in the wires if the direction of current is reversed keeping the magnetic field same as before ? (Ignore the mass of the wires) g = 9.8 ms^-2

A box is to be made from a sheet 12times12 sq.cm, by cutting equal squares from the four corners and turning up its sides. Find the length of the side of the square to be cut out, in order to obtain a box of the largest possible volume? a)6 b)4 c)3 d)2

A steel wire of length 5 m and area of cross-section 4 mm^(2) is stretched by 2 mm by the application of a force. If young's modulus of steel is 2xx10^(11)N//m^(2), then the energy stored in the wire is