ACT Science conflicting viewpoints practice

Newton's First Law of Motion

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

True or False: A force is required to maintain motion.

False - According to Newton's First Law, no force is needed to maintain constant velocity.

Newton's Second Law of Motion formula

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

Cause → Effect: Increasing mass with constant force.

Effect: Acceleration decreases. More mass requires more force for the same acceleration.

What does Newton's Third Law state?

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

Fill in the blank: An object will accelerate in the direction of the _____ applied.

net force

Difference between mass and weight.

Mass is the amount of matter (kg), weight is the force due to gravity (N). Weight = mass × gravity.

Example of Newton's First Law

A book on a table remains at rest until someone pushes it.

What is inertia?

The tendency of an object to resist changes in its state of motion.

True or False: Acceleration can happen without a net force.

False - Acceleration requires a net force according to Newton's Second Law.

How to calculate force if mass is 5 kg and acceleration is 2 m/s²?

Use $\displaystyle F = ma$: $\displaystyle F = 5 ext{ kg} imes 2 ext{ m/s}^2 = 10 ext{ N}$.

Comparison: Contact force vs. Action-at-a-distance force.

Contact force requires physical interaction (friction). Action-at-a-distance force acts over a distance (gravity).

What is terminal velocity?

The constant speed an object reaches when the force of gravity is balanced by drag force.

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

Newton (N)

Cause → Effect: Increasing force while mass remains constant.

Effect: Acceleration increases proportionally.

Newton's Law: Objects in motion tend to stay in _____ motion.

uniform

Work formula?

Work (W) = Force (F) × Distance (d) × cos(θ). Units: Joules (J).

True or False: Work is done only when force is applied.

True - Work is defined as force causing displacement.

Fill in the blank: Kinetic energy (KE) = _____

KE = $\displaystyle \frac{1}{2} mv^2$, where m is mass and v is velocity.

Difference between kinetic and potential energy?

Kinetic energy: energy of motion. Potential energy: stored energy based on position.

Cause of energy transformation?

Work done on or by an object causes energy transformation between forms.

Question: What is potential energy's formula?

Potential Energy (PE) = mgh, where m = mass, g = gravity (9.8 m/s²), h = height.

True or False: Energy can be created.

False - Energy cannot be created or destroyed, only transformed (Law of Conservation of Energy).

Example of work done?

Lifting a 10 lb box 2 feet: W = F × d = 10 lb × 2 ft = 20 ft-lb.

What is mechanical energy?

Mechanical energy is the sum of kinetic energy and potential energy in a system.

Question: If force doubles, what happens to work?

Work doubles as W = F × d; if F doubles and d is constant, W doubles.

Heat energy is a form of _____

Heat energy is a form of kinetic energy at the molecular level.

Comparison: Elastic vs. Gravitational Potential Energy

Elastic: energy stored in stretched/compressed objects. Gravitational: energy based on height.