Newton's 3 Laws of Motion

By Emily Quinn and Liana Rodriguez

Vocab Words

Units: Newton (N)

Force: A push or pull

Mass: The amount of matter in an object

Inertia: An object resisting to change motion

Acceleration: Increase of rate speed or something

Newton’s First Law:

Newton’s first law of motion states that any object that is at rest will stay at rest until an unbalanced force is applied. It also states the same for an object in motion. An object in motion will stay in motion until an unbalanced force is applied. This law is also known as the law of inertia. When objects have more inertia, there will need to be a greater force acting on that object.

This picture shows the first law because an object (the rocket) will stay at rest until an external force is applied (the engines)

Real Life Example of Newton’s First Law: When sliding a hockey puck, the puck will stop due to the friction of the ice. If the ice didn’t provide a friction, the puck will continue to move. In this case, the ice is the unbalanced force applied onto our object.

Newton's Second Law:

Newton’s second law of motion says that acceleration depends on two things. Acceleration depends on the mass of the object and the net force that’s being applied to the object. If the mass decreases, acceleration will be increased. When mass increases, the acceleration begins to decrease. An equation for this relationship can be expressed as: Acceleration = Net Force / Mass. An object’s acceleration will increase when the force increases. Acceleration is measured in meters per second per second (or just m/s2). Mass is measured in kilograms. Since force is measured by kilograms x m/s2. The unit of force would therefore become newton. One newton is the amount of force that is required to accelerate a single kilogram of mass for 1 m/s2.

Example equation: a=300N / 201 kg (answer would be 1.49 m/s2)

This picture shows the third law because if mass (the elephant) is larger than the amount of force (the human), then there will be little to no acceleration.

Real Life Example of Newton’s Second Law: It would be easier to push a shopping cart that is empty compared to a shopping cart that’s full. The empty shopping cart would have less mass and a small force can be applied to move it. To move the full shopping cart, greater force would be required than to move the one that’s empty.

Newton's Third Law:

Newton's third law says that for all actions, there will be an equal and opposite reaction. There is always a pair of forces that act upon two objects that are interacting. Forces always come in pairs.

This picture shows the third law because with every action (applying force to the diving board) there is a reaction (the diving board accelerating you into the air).

Real Life Example of Newton’s Third Law: When jumping off of a small rowboat, you push yourself forward off of the boat. The same force that pushes you forward is the force that will cause the boat to be pushed backwards.