Forces and Motion Box


Physical objects are part of an interactive system mediated by forces, which are governed by Newton’s laws.  This unit teaches students to recognize different types of forces, their effects on an object’s motion, and how Newton’s laws describe these effects.  To guide students in understanding these concepts, the unit poses several essential questions:

  • How does the motion of a rock thrown in outer space differ from the motion of a rock thrown on Earth?  On other planets?
  • Where in the solar system would you be able to jump the highest?  The least high?  Why?
  • If a horse pulls on a cart and the cart pulls on the horse, why don’t the two forces cancel out?
  • How do multiple forces affect an object’s motion?

Learning Objectives

Students will understand that. . .

  • Real-life conditions on Earth, such as the presence of air resistance and other forms of friction, make it difficult to observe Newton’s first law
  • All objects are subject to a number of outside forces, and the motion of the objects depends on the combination of the force

Students will know. . .

  • Vocabulary (force, net force, balanced/unbalanced forces, gravity, friction, tension, compression, mass, weight)
  • Newton’s laws (recognize and state/paraphrase)

Students will be able to. . .

  • Create a qualitative free-body diagram showing forces acting on stationary and moving objects
  • Identify applications of Newton’s laws in real-life situations
  • Identify differences in forces acting on a moving object in outer space versus on Earth or other planets, and offer a reasoned hypothesis about how each would move
  • Analyze data on the masses of planetary bodies and explain the effect of planetary mass on gravity and the effect of gravity on potential jump height