Explain how Newton's law of inertia describes the motion of objects.
Newton's law of inertia states that an object at rest stays at rest, and an object in motion continues moving at a constant speed and in a straight line, unless an unbalanced external force acts on it.
Explain what is meant by the term mechanical advantage.
Mechanical advantage is the ratio of the output force to the input force. It shows how much a machine multiplies the force applied to it.
Explain why a seesaw is closest in arrangement to a first class lever.
A seesaw is like a first-class lever because its fulcrum is positioned between the effort applied on one side and the load on the other side.
Describe the four main types of resistance forces.
The four main resistance forces are objects with mass, inertia, and momentum; friction; gravity; and air resistance. Objects with mass are able to provide resistance by colliding with other objects. Friction slows objects down by providing a steady resistance when the objects are in contact with and rubbing against a surface. Gravity provides a steady downward pull towards the center of Earth's mass. Air resistance is the cumulative force provided by millions of oxygen atoms being displaced.
Explain what distinguishes first class levers from second and third class levers.
First-class levers have the fulcrum between the effort and the load. Second-class levers have the load between the fulcrum and effort, while third-class levers have the effort between the fulcrum and load.
How might being too strong actually restrict a joint's range of motion?
If excess muscle is too bulky it can interfere with the motion of a joint, which means that too much muscle strength can reduce a joint's range of motion and can actually reduce flexibility.
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