Newton’s Laws of

Motion

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

Take a look at each of the following terms associated with water movement and make an argument for which of Newton’s Laws is at work.

Standing Wave

Water moving in opposite directions toward each other can create a standing wave.

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

Standing Wave

Newton’s Third Law of Motion:The slow-moving water is being forced back into the opposite direction.

Pool Drop

Calm water spills over into rapids,

then becomes calm again.

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

Pool Drop

Newton’s First Law of Motion: The current is the

external force that is moving the water over the rocks.

Newton’s Second Law also applies;

the water is accelerating

because of the downward fall.

Eddies

Current of water running contrary to the main current.

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

EddiesNewton’s Third Law of Motion: the water flows back upstream because it is reacting to striking an obstacle.

PillowsDescribes the layer of slack water on rocks and other obstacles.

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

Pillows

Newton’s First Law of Motion: the water is lying on the rock until more water pushes it off.

Sieves

Water flows through an underwater opening (typically in a formation of rocks) that is not necessarily large enough for a person or boat to move through.

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

Sieves

Newton’s Second Law of Motion; the water accelerates through the rocks when it moves downward.

Hydraulics

Water flows over a rock or obstacle and then back onto itself. This dynamic can flip a raft, or in milder motion can provide a surfing effect.

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

Hydraulics

Newton’s Third Law of Motion; the water is bouncing back off a rock onto itself; an equal and opposite reaction.

Command“All Forward”

Everyone takes one stroke forward.

First LawEvery object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second LawThe relationship between an object’s mass (m), its acceleration (a), and the applied force (F) is F = ma. Acceleration and the force are vectors; in this law the direction of the force vector is the same as the direction of the acceleration vector.

Third LawFor every action there is an equal and opposite reaction.

“All Forward”Newton’s First Law of Motion; when the rafters paddle forward, the boat moves forward due to an external force.