1.33 use the relationship between orbital speed, orbital radius and time period

By using this relationship, we can calculate the orbital speed of planets if we know it's distance from the Sun and the time it takes for one orbit around the Sun.

Therefore,  using the information from this table, we can calculate each planet's orbital speed.

The results are shown in this table:

Now, we can draw up a graph showing the orbital speed of different planets, against their distance from the Sun.

Questions
1. Compare the speeds of planets closest to the Sun to those further away
The closer to the Sun, the faster the planet's orbital speed

2. Explain the difference
The speed of which a planet orbits is proportionate to the Sun's gravitational force. The greater the gravitational force, the more 'force' planets experience and hence gains more velocity, and because gravitational force of the Sun decreases as distance increases (due to the 'inverse square law' of gravity), the further away a planet is from the Sun, the slower its orbital speed.

http://www.newton.dep.anl.gov/askasci/ast99/ast99121.htm
http://www.newton.dep.anl.gov/askasci/phy05/phy05071.htm