1. Is work (as a scientific term) being done in the following examples? Explain your answer in each case. (6)
   • A hiker puts her backpack on.
   • A gardener pulls on a large weed as hard as he can, but he can't get it out of the ground.
   • A student memorizes a poem.
2. You use a force of 40 N to push a box of books 3.2 m along the floor. How much work have you done? Show your calculation. (4)
3. Use an example to explain the effect of friction on a machine. (2)