Four uniform solid cubes of edges 10 cm, 20 cm, 30 cm and 40 cm are kept on the ground, touching each other in order. Locate centre of mass of their system.

Two brass sphere of radii 5 cm and 10 cm are brought in contact with each other. Find the centre of gravity of the combination.

If two convex lenses of focal lengths 10 cm and 5 cm are kept in contact with each other , What is their combined focal length ?

How many solid cylinders of radius 10 cm and height 6 cm can be made by melting a soilid sphere of radius 30 cm?

A cylindrical vessel of 100 cm height is kept filled upto the brim. It has four holes 1,2,3,4 which are respectively at heights of 27 cm, 30 cm , 50 cm and 80 cm from the horizontal floor. The water falling at the maximum horizontal distance from the vessel comes from

Two thin converging lenses of focal length 15 cm and 30 cm are held in contact with each other. The focal length of the combination is

Two soap bubbles of radii r_1 and r_2 equal to 4cm and 5 cm are touching each other over a common surface S_1S_2 (shown in figure.) Its radius will be

Two circles having radii 3.5 cm and 4.8 cm touch each other internally.Find the distance between their centres.

If a concave lens of focal length 12 cm and a convex lens of focal length 20 cm are kept in contact with each other . (i) Find be the focal length of the combination ? (ii) What will be the behaviour of the combination ?

Two lenses with focal length 20 cm and - 10 cm are placed together. Determine the power of combination.