Why does the velocity increase when liquid flowing in a wider tube enters a narrow tube?

Name the three types of thermal expansion.

The poisson ratio of a material is 0.5 if a force is applied to a wire of this material, there is a decrease in the cross sectional area by 4% what is the percentage increases in the length.

For a given material, the youngs modulus is 2 - 4 times that of rigidity modulus. What is its poisson's ratio?

A wire of length L and cross section A is made of material of youngs modulus y. It is stretched by an amount x. What is the work done?