Introducing the Adam’s Flex System

I know nothing about grinders and this is a new house that sits down below the street. If the electricity should fail during a storm and I don’t use the water system, can heavy rain run into the tank and fill it causing the toilets and drains to back up?

How big usually are these holding tanks?
The house is about 1500 sq ft. I am just wondering if I am overly worried about a back up from normal Florida thunderstorms.

Down in the basement of Art 101, Felix Mathias has set up a production area for mixing up batches of colored cement rock mold bricks. The wet cement is poured into plastic molds, that are held in a wood framework tray. An electric sander is then used to shake the air bubbles out of the mix. Once the cement is dry, it is taken out of the molds & collected on to pallets until we have enough for our projects. This film shows the start-up version of how this process works and the next will show how the process has progressed as he has become more efficient and better skilled at it. Music by Jeff Young.

I’m having difficulty with this question can someone please help.

Q)
A handyman is using an electric sander with a rechargeable battery. He charges up the sander with 2500J. It should require 20J of energy to sand each m² of surface. At the end of three hours, the rechargeable battery is exhausted. He checks his work and finds he has actually covered 100m².
a)How much useful energy has been put into sanding?
b) What is the efficiency of the machine?

Thank you

p.s. Efficiency formula is:
% efficiency = input/ouput x 100
I have had a try at dong the question myself but the results don’t seem right to me. I’m don’t want someone to ‘do it for me’. I just want to hopefully see where i’m going wrong and complete the work as its due in tommorow and i have an exam tommorow morning so i’d like to understand it by then.

Here’s my answer, i don’t know where i’m going wrong but i know it is wrong.

a) 20J x 100 = 2000J (useful energy).

b) output/input x 100 = 2000/2500 x 100 = 80%

Home Improvement: Power Tool Pursuit! is an action/platforming video game for the Super Nintendo Entertainment System very loosely based on the hit sitcom Home Improvement. A version for the Sega Genesis was made but was never released. Sega rejected the game, as it would be the same as the SNES version.

To see the full review, visit www.thewoodnerd.com A look at the various sanding modes of the RO 90 DX sander and how they affect the behavior of the sanding pad