The hollow sphere, in which the circus motor cyelist performs his stunts ,has a diameter of 7m. Find the area available to the motor cyclist for riding.

Find the diameter of a sphere whose surface area is 154m^(2) .

A uniformly charged conducting sphere of 2.4 m diameter has a surface charge density of 80.0muC//m^(2) . a. Find the charge on the sphere. b. What is the total electric flux leaving the surface of the sphere?

A shuttle cock used for playing badminton has the shape of a frustum of a cone is mounted on a hemisphere. The diameters of the frustum are 5 cm and 2 cm. The height of the entire shuttle cock is 7 cm. Find its external surface area.

The two wires shown in figure are made of the same material which has a breaking stress of 8xx10^8Nm^-2 . The area of cross section of the upper wire is 0.006 cm^2 and that of the lower wire is 0.003 cm^2 . The mass m_1=10 kg , m_2=20kg and the hanger is light. a. Find the maximum load that can be put on the hanger without breaking a wire. Which wire will break first if the load is increased? b. Repeat the above part m_1=10 kg and m_2=36kg .

a. The top of the atmosphere is at about 400 kV with respectto the surface of the earth, corresponding to an electric field that decreases with altitude. Near the surface of the earth, the field is about 100 Vm^(-1). Why then do we not get a electric shock as we step out of our house into the openy (Assume the house to be a steel cage so there is no field inside!) b. A man fixes outside his house one evening a two metre high insulating slab carrying on its top a large aluminium sheet of area 1m^(2) . Will he get an electric shock if he touches the metal sheet next morning? c. The discharging current in the atmosphere due to the small conductivity of air is known to be 1800A on an average over the globe. Why then does the atmosphere not discharge itself completely in due course and become electrically neutral? In other words, what keeps the atmosphere charged? d. What are the forms of energy into which the electrical energy of the atmosphere is dissipated during a lightning? (Hint: The earth has an electric field of about 100 Vm^(-1) at its surface in the downward direction, corresponding to a surface charge density =-10^(-9) Cm^(-2) ?.

A car has two wipers which do not ovarlap. Each wiper has a blade of length 25cm sweeping through an angle of 115^(@) . Find the total area cleaned at each sweep of the blades. (usepi=(22)/(7))

A golf ball has diameter equal to 4.1 cm. Its surface has 150 dimples each of radius 2 mm. Calculate total surface area which is exposed to the surroundings. (Assume that the dimples are all hemispherical) [pi = (22)/(7)]