Big Ideas for Forces and Motion
Newton's laws of motion, relations between the forces acting on a body and the motion of the body, first formulated by English physicist and mathematician Sir. Newton's second law of motion is closely related to Newton's first law of motion. It mathematically states the cause and effect relationship between force and. Explore the relationships between ideas about force and acceleration in the Concept Development Maps – Laws of.
A simple mathematical relationship exists between the mass of an object mthe net force on the object f and its acceleration a. They can then be asked to identify all the actual forces and the net force on objects in a wide range of motion contexts.
In particular, the role of friction needs to be explored because it has such a huge influence on the observed motion of everyday objects. Ideas about friction are explored in the focus idea Friction is a force.
Open up discussion via a shared experience POE Predict-Observe-Explain can be used to develop powerful understandings about balanced and unbalanced forces. Using a bicycle wheel mounted as a pulley, with a bucket of sand hanging from either side, students can respond to each question below.
They should observe what happens and then explain their observation: With one bucket A higher than the other Band both held stationary, ask the students which weighs more.
With A pulled down so it is level with B, ask students to predict what will happen when you let go of A.
Return to 1 and ask for student predictions about the effect of adding a small weight to B — will either side move, how far?
- Newton's understanding of forces and motion
- Newton's Second Law
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The same as set up as above, but with a much heavier weight so it will cause movement. Explore the effects of adding and subtracting large and small weights while the buckets are moving. There are several possibilities here which can foster greater student engagement if they are encouraged to suggest some of these new possibilities.
E Place a puck on air table and ask students to predict how they would keep it moving at a steady speed by pushing on it with a ruler. Most students are surprised that it is impossible to achieve a steady speed with this action and are intrigued as any amount of push with the ruler makes the puck keep 'running away from them'. Promote reflection on and clarification of existing ideas Road safety is a topic where students can explore the issues associated with mass and speed of vehicles involved in car accidents and how these may influence the injuries inflicted on passengers.
Encourage students to think of the advantages of introducing light weight vehicles and the disadvantages of being involved in collisions with much heavier trucks. The Digilearn objects below provide some simulations students can experiment with. Identify situations and discuss these in class. Utilise software programs that can analyse video or digitally recorded motion. Accelerate - Pilot a spaceship between planets.
Use Newton's second law of motion to work out the acceleration needed in a series of challenges. Drive at a constant acceleration, then make adjustments for cargo and friction.
Competency Forces and Motion and their Relationships | BioEd Online
A force applied to a body can change the magnitude of the momentum, or its direction, or both. If a body has a net force acting on it, it is accelerated in accordance with the equation.
Conversely, if a body is not accelerated, there is no net force acting on it.
The third law is also known as the law of action and reaction. This law is important in analyzing problems of static equilibriumwhere all forces are balanced, but it also applies to bodies in uniform or accelerated motion. The forces it describes are real ones, not mere bookkeeping devices. For example, a book resting on a table applies a downward force equal to its weight on the table.
Newton's laws of motion
According to the third law, the table applies an equal and opposite force to the book. This force occurs because the weight of the book causes the table to deform slightly so that it pushes back on the book like a coiled spring. In Nicolaus Copernicus suggested that the Sun, rather than Earth, might be at the centre of the universe.