Describes how simple machines utilize the principle of the slope or incline to plow fields, unlock doors, and lift heavy loads. This description may be from another edition of this product.
ThriftBooks sells millions of used books at the lowest everyday prices. We personally assess every book's quality and offer rare, out-of-print treasures. We deliver the joy of reading in recyclable packaging with free standard shipping on US orders over $15. ThriftBooks.com. Read more. Spend less.