What is the mass of water required to fill a circular tub 2.6m in diameter and 1.6m deep?

Question

Answer in units of kg.

I kinda forgot how to do this... all I remember is that V=pi*r^2*h which gives me 8.49487 cubic meters?

Answer 1

As you have:

V = pi * r² * h

= 3.14159265 * (1.3 m)² * 1.6 m

= 8.49487 m³

Density of water @ 4 °C = 1000 kg/m³

8.49487 m³ * 1000 kg/m³ = 8.49487e3 kg

Edit: I was composing my answer when you asked the follow up. Yes, you need to know the density. It's actually 999.9749 kg/m³ @ 4 °C, but 1000 is close enough.

Answer 2

That's what I got.  It seems right.