Classical Mechanics

# Work: Level 2 Challenges

In July 2015, the satellite New Horizons flew close by Pluto, capturing detailed, never seen before images of the dwarf planet and its moons.

How are artificial satellites like New Horizons steered in space?

You bend your knees before jumping. Then you push the ground downwards to jump. What is the work done by the normal reaction on you during the push?

##### Inspired by Steven Chase

You are shrunk to the height of a small pebble and thrown into a blender. Your mass is reduced so that your density is the same as usual. The blades start moving in 60 seconds and you'll die if you stay at the bottom. What would you do?

One valid but counterintuitive answer is to jump out of the blender.

Suppose a person of height 1.80 m and mass 60 kg can jump to the height of 60 cm. If this person is shrunk to one thousandth of his original size, how high is he now able to jump in centimeters?

Assumptions

• The amount of power a human can generate is proportional to the muscle mass $m$.

A heavy box was kept on a smooth floor, initially at rest. I started moving it in a circular path, and then brought it to rest when it completed one revolution.

How much work did I do on the box?

A heavy box was kept on a rough floor, initially at rest. I started moving it in a circular path, and then brought it to rest when it completed one revolution.

Fill in the blank with the most appropriate choice:

The work performed ________.

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