ACT Science outside knowledge facts review

What is Newton's First Law of Motion?

An object at rest stays at rest, and an object in motion stays in motion unless acted upon by a net external force.

Example of inertia in daily life?

A passenger lurches forward in a car that suddenly stops due to inertia.

Newton's Second Law formula?

$\displaystyle F = ma$, where F is net force, m is mass, and a is acceleration.

True or False: Mass is the same as weight.

False. Mass is the amount of matter, while weight is the force of gravity on that mass.

What does Newton's Third Law state?

For every action, there is an equal and opposite reaction.

Cause → Effect: Pushing a wall.

Cause: You push the wall. Effect: The wall pushes back with equal force.

Fill in the blank: Mass affects __________.

acceleration, according to Newton's Second Law.

How do seatbelts relate to Newton's First Law?

They provide the external force needed to stop passengers' inertia during a sudden stop.

Compare mass and weight.

Mass: measured in kg. Weight: measured in pounds (lb) and depends on gravity.

Example of action-reaction pair?

Jumping off a small boat: You push down on the boat, it pushes you up.

What happens if no net force acts on an object?

It maintains its state of motion (either at rest or moving uniformly).

How does friction relate to Newton's laws?

Friction is the force opposing motion, affecting acceleration and direction based on Newton's laws.

True or False: A heavier object accelerates faster than a lighter one.

False. Heavier objects require more force to accelerate the same amount as lighter objects.

Example of Newton's Second Law in action?

A car accelerates faster than a truck when the same force is applied.

Fill in the blank: The unit of force is __________.

the Newton (N), defined as kg·m/s².

What role does air resistance play?

It acts as a force opposing motion, affecting acceleration and final speed.

What is a force?

A force is an interaction that causes an object to change its motion. It can be a push or a pull.

True or False: All forces cause motion.

False. A force must overcome other forces (like friction) to cause motion.

List two types of forces.

1. Gravitational force 2. Frictional force

What is friction?

Friction is the resistance that one surface or object encounters when moving over another. It opposes motion.

Cause → Effect: What happens when a net force acts on an object?

The object will accelerate in the direction of the net force according to Newton's second law.

Fill in the blank: The _____ is the force that pulls objects toward each other.

Gravitational force

What is the formula for calculating net force?

Net force is calculated as: $\displaystyle F_{net} = F_{1} + F_{2} + ... + F_{n}$.

Comparison: Contact forces vs. non-contact forces.

Contact forces result from physical contact (like friction), while non-contact forces act at a distance (like gravity).

What is inertia?

Inertia is the tendency of an object to resist changes in its state of motion. It depends on mass.

Cause → Effect: What happens when friction is reduced?

Objects will move more easily and accelerate faster for the same applied force.

True or False: Mass affects weight.

True. Weight is the force of gravity on an object’s mass: $\displaystyle W = mg$.

What is acceleration?

Acceleration is the rate of change of velocity of an object, calculated as $\displaystyle a = \frac{F}{m}$.

List three factors affecting the force of friction.

1. Surface texture 2. Normal force 3. Material properties

What is the role of air resistance?

Air resistance opposes the motion of objects moving through the air, affecting their acceleration.

Fill in the blank: The unit of force is the _____.

Newton (N)

What happens when two equal forces act in opposite directions?

They cancel each other out, resulting in a net force of zero, and no motion change.