# force

Forces are everywhere. Forces are a push or pull on an object. They can be due to phenomena such as [/Gravity Gravity], [/Magnetism Magnetism], or anything that might cause a mass to accelerate.

Force can be a push or pull. A force is any influence that causes an object to change its movement, direction, or geometrical construction. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate, or which can cause a flexible object to deform. A force has both magnitude and direction, making it a vector quantity.

Some forces are easy to understand. Multiple forces such as gravity and friction combine to make the net force.

The different types of force are static load, dynamic load, internal resistance, tension, compression, shear and torsion.

• A New Angle on Force (images) – explore forces that are directed at angles to the horizontal and vertical.

May the force be with you
Introduction to Forces (video 8:26)
Friction (video 11:35) – An introduction to friction and coefficient of friction.

The diagrams show a block on a flat surface and an inclined plane. Forces are resolved and added together to determine their magnitudes and the net force.

• Ask – Multiple forces such as gravity and friction combine to make the net force. What are forces are all around us?
• Imagine – Some force is good and we need more. Other forces we want to reduce. What are some ways to increase force? How can force be reduced?
• Plan – In general, the total of all forces on an object are equal to zero if the object is not moving. What are some ways to get a moving object to stop? What forces are needed?
• Create – An object can move if more force is applied OR if less force is applied. How are forces measured? How can force be removed?
• Improve – Are there better ways to tell what forces are acting on an object?

That’s engineering

• air resistance – air pushing on a moving object which slows it down.
• Free-body diagram – diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation. A free-body diagram is a special example of the vector diagrams

Engineering ideas

• net force, vectors, gravity, electromagnetic, atomic/ nuclear, friction, tension, elastic, torque,

Do it
Now it is your turn. Here are some challenges for you to work on…

• Roller Coaster Designer – Bend and shape the track of your roller coaster to send passengers on a thrilling, yet safe ride.
• think about a hot air balloon and an airplane. What forces are the same? What are different? Look this up if you need to find the information. Illustrate your findings.
• Touchdown Challenge – Design and build a shock-absorbing system that will protect two “astronauts” when they land. Follow the engineering design process to design and build a shock-absorbing system out of paper, straws, and mini-marshmallows; attach the shock absorber to a cardboard platform; and improve the design based on testing results.
• Monster Physics (interactive simulation, app, free (lite)) – comes with 50 missions to solve including simple tutorials as well as mind-bending challenges. Many of the missions are open-ended and can be solved with a wide variety of different solutions