We can see that the difference between each term is 3, so we know that the nth term takes the form of 3n+c, where c is some number. We find c by comparing our sequence of numbers with 3n: 3,6,9,12,15. Comparing 3 to 7 we see that we have to add 4 (we can also look at the other terms to see if this works, eg 6 and 10, 9 and 13, 12 and 16, 15 and 19). So c=4. Therefore the nth term is given by 3n+4... more

We can see that the difference between each term is 3, so we know that the nth term takes the form of 3n+c, where c is some number. We find c by comparing our sequence of numbers with 3n: 3,6,9,12,15. Comparing 3 to 7 we see that we have to add 4 (we can also look at the other terms to see if this works, eg 6 and 10, 9 and 13, 12 and 16, 15 and 19). So c=4. Therefore the nth term is given by 3n+4... more

Work done (J) = force (N) x distance (m) So WD = 0.21 x 0.3m = 0.063N.

All matter consists of particles. Since air is made up of many gas particles, such as oxygen and carbon dioxide, air is classed as one of the three states of matter.