Question

Explain why objects moving in fluids must have stream-line shapes.

Answer 1

so that they can cut the stream and easily move through it and they can move smoothly by reducing friction due to its streamline shape

Answer 2

because the frictional force depends on the shape of the body. By giving objects a special shape, that is streamlined shape, the force of friction acting on it can be minimised. Hence, it becomes easier for the body to move through the fluid.

I hope it is correct....