Kiddom 8.1 Unit Test

Collision

An event in which two or more bodies exert forces on each other over a relatively short period of time.

Force

A push or pull exerted on an object resulting from its interaction with another object, measured in newtons ($\text{N}$).

Kinetic energy

The energy possessed by an object due to its motion.

Damage

Physical harm or permanent structural alteration caused to a body or material as a result of an applied force.

Contact force

A force that acts on an object only when touching it directly.

Deform

To alter the size, shape, or structural dimensions of an object under the influence of an applied mechanical load.

Line of best fit

A straight or smooth line drawn through data points on a scatter plot that best represents the general trend.

Elastic limit

The threshold of stress beyond which a material will suffer permanent deformation rather than returning to its original shape.

Breaking point

The critical stress level at which a material fails completely and splits apart. Partially or into multiple pieces.

Independent variable

The condition or factor in an experiment that is deliberately controlled and changed by the scientist.

Dependent variable

The measurable factor in a scientific investigation that changes in response to the changes made by the scientist. The result that the scientist measures.

Peak force

The absolute maximum magnitude of force experienced during an impact or collision event.

Free body diagram

An illustration showing an isolated object and all external forces acting upon it.

Stored (potential) energy

Energy retained by an object as a consequence of a change in its shape or position.

Air resistance

The opposing force exerted by air particles on a moving object.

Friction

The opposing force exerted on any object through contact with another object as it travels over it.

Newton's first law of motion

An object remains at rest or continues to move at a constant velocity unless acted upon by an external force.

Newton's second law of motion

The principle stating that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Defined by the formula $F = m a$.

Newton's third law of motion

The principle stating that when one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body. (During a collision, both objects feel the exact same amount of force.)

When I push against the ground, what is the reaction force?

The ground pushes back with an equal and opposite force. (It pushed me in to the air.)

If I push a box with 10 newtons of force to the right, and friction generated 5 newtons of force to the left, what is the net force acting on the box?

5 newtons to the right

I’m running at the same speed as a turtle. We’re running right next to each other. How does the turtle move in relation to me?

The turtle appears to barely move because it stays right next to me.

I stop running the turtle keeps going. How does the turtle move in relation to me?

The turtle appears to move quickly past me. (Because it does.)

I start running really fast and leave that stupid turtle in the dust. How does the turtle move in relation to me?

The turtle appears to move backwards away from me as I run past it.

If I’m riding in the back of a truck and toss a ball up and down what does the ball appear to do?

go up and down

If is see someone riding the back of a truck going the right tossing a ball up and down, what does the ball appear to do?

go up, to the right, and then back down

Mass is ________ _________ to KE.

directly proportional (If I multiple mass by 3, KE is multiplied by 3)

KE is proportional to the square of whatever you multiple the _______ by.

speed (If I multiple speed by 3, KE is multiplied by 9)

Air resistance pushes ________ moving objects and causes them to move ________.

against, slower

If a car encounters lots of air resistance, it takes _____ fuel to maintain speed while pushing against that resistance.

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