Mr. Sludge, president of Robocorp, accuses robot lifter-upper Mary Murray of being the laziest worker in the company. Very loudly.

Mary's co-worker, Joe Shmo, is always sweaty and smelly. Mary is never sweaty or smelly, so Joe must work harder than she does, Mr. Sludge says.

Mary is demoted to work in the deep, dark Pit. All Mary can do now is try to prove her case in Science Court.

In Science Court, attorney Doug Savage says Mary must be a lazy worker. Not only is Mary not as smelly as Joe, but she reads while she's at work!

Alison Krempel argues that, scientifically speaking, Mary does just the same amount of work as Joe Shmo.

Is Mary really the laziest worker at Robocorp? Or can Professor Parsons show that she has found an easier way to do her job?

Science Court challenge question:

Scientifically speaking, which is more work, reading a 300 page book or pushing against a wall that won't move?

Before you answer... try these simple experiments.

Jumping Coins

You'll need

• ruler
• pencil
• two large coins

What to Do

1. Place the pencil under the middle of the ruler and put a coin on one end.
2. Drop the second coin from a height of about one foot so it hits the other end of the ruler at about the three inch mark. Observe what happens.
3. Next, from the same height, drop the second coin again at the very end of the ruler.
4. Notice that the closer to the end of the ruler the dropped coin falls, the higher the other coin jumps. The greater the distance, the more force is exerted.

Ask
Professor
Parsons

Click Professor Parsons for a scientific explanation of work.

Roll Out the Barrow

You'll Need

• plastic bag
• short pencil
• thread spool
• tape
• small stones
• shoe box
• two equal lengths of wood, or two rulers

What to Do

1. Put the stones in the plastic bag and lift them. Observe the amount of force, or effort, you must exert to lift the stones.
2. Tape the two pieces of wood or two rulers to the bottom of the box, one on either side. Leave the ends sticking out, like wheelbarrow handles.
3. Make a wheel by sticking the pencil through the spool.
4. Tape the pencil crosswise to the ends of the wood.
5. Put the bag of stones in the barrow, close the the wheel. Try lifting it. It's easier to lift the stones when they are in the wheelbarrow than it was to lift them without the wheelbarrow. The wheelbarrow acts as a lever. When you use a lever, your hands move farther than the distance the load moves. The amount of force you need to use to lift the stones is less, but it is spread out over the longer distance created by the lever.