Systems of Particles and Rotational Motion — Physics STD 11 Science — Question

The density of oxygen is 16 times the density of hydrogen. What is the relation between the speeds of sound in two gases?

A diverging lens of focal length 20cm and a converging mirror of focal length 10cm are placed coaxially at a separation of 5cm. Where should an object be placed so that a real image is formed at the object itself?

Why does air bubble in a liquid rise up?

Which is the suitable instrument among screw gauge and spherometer to measure the curvature of the plane?

Torque acting on a body is equal to rate of change of _______.

What is the reason of making the shape of shaft like I?

When air is blown in between two balls suspended close to each other, they are attracted towards each other. Give reason.

A labourer standing near the top of an old wooden step ladder feels unstable. Why?

Can the relative velocity of one moving object be zero compared to another moving object? Give any example.

Rubber tyres are preferred over steel tyres. Why?