A large ballon of volume `1425 m^3` is used to lift a payload of 400 kg. Assuming that the ballon maintains constant radius as it rises. How high does it rise? `(Take Y_0 = 8000 m` and `rho_(He) = 0.18 kg m^-3)`

If you apply 1 J of energy to lift a book of 0.5 kg, how high will it rise?

A constant retarding force of 50 N is applied to a body of mass 20 kg moving initially with a speed of 15m s^-1 . How long does the body take to stop ?

A steel wire of mass mu per unit length with a circular cross section has a radius of 0.1 cm. The wire is of length 10 m when measured lying horizontal, and hangs from a hook on the wall. A mass of 25 kg is hung from the free end of the wire. Assuming the wire to be uniform and lateral strains < < longitudinal strains, find the extension in the length of the wire. The density of steel is 7860 kg m^-3 (Young's modulues Y = 2 xx 10^11 N m^-2)

An air bubble of volume 1.0 cm^3 rises from the bottom of a lake 40 m deep at a temperature of 12^@C . To what volume does it grow when it reaches the surface, which is at a temperature of 35^@C ?

A heating coil is immersed in a 100 g sample of H_(2)O (l) at a 1 atm and 100^(@) C in a closed vessel. In this heating process , 60% of the liquid is converted to the gaseous form at constant pressure of 1 atm . The densities of liquid and gas under these conditions are 1000 kg//m^(3) and 0.60 kg//m^(3) respectively . Magnitude of the work done forthe process is : (Take : 1L-atm= 100J)

A body of mass 0.8 kg is whirled uniformlyt at the end of a string 2 m long.If teh string makes 3 revolutins in 1.5 sec,calculate the tension in the string.