Weight is the name we give to the force of gravity which is the force that attracts objects to the ground. In fact, it is a force between an object and the globe- planet earth. Since objects falling always have an acceleration of approximately 9.8 m/s2, Newton's second law means if we know the mass of an object we can calculate the weight and vice versa.
This means that mass has two separate properties. Mass is measured with a beam balance which works because the force of gravity acts on the object whose mass we want to measure. Mass is also that property of an object that makes it hard to accelerate. We speak of inertial mass and gravitational mass.
  1. What is inertia?
  2. The mass of an object is the same wherever it is measured, but the weight depends slightly on location. Why?
  3. What is the weight of a 1 kilogram object?
  4. Convert the following to weights or mass: 10 kgm , 4 kgm, 4 Newtons, 10 Newtons.
  5. Why is the unit of mass in the English system called the "slug".
  6. How much force is needed to keep a 20-N stone from falling?
  7. On the moon the force of gravity is 1/6 the force of gravity on earth. What is the weight of a 10 kg object on the earth? What is the mass and weight on the moon?
  8. As a skydiver falls faster and faster does the net force on her increase, decrease or remain the same? Does her acceleration increase, decrease or remain the same.