Force and Laws of Motion - Practice Flashcards

A set of practice Q&A flashcards covering inertia, Newton's laws, momentum, force units, friction, and related concepts from the Force and Laws of Motion notes.

What is inertia and how is it related to mass?

Inertia is the natural tendency of an object to resist a change in its state of rest or motion; mass is a measure of this inertia.

State the First Law of Motion (Law of Inertia).

An object remains in a state of rest or of uniform motion in a straight line unless compelled to change that state by an applied force.

What is meant by balanced forces?

Two opposite forces of equal magnitude acting on an object, producing zero net external force and no change in motion.

What is meant by unbalanced forces?

Opposing forces that are not equal, resulting in a net external force and a change in motion (acceleration) of the object.

What is the Second Law of Motion (Newton's Second Law)?

The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force; for constant mass, F = ma.

Define momentum and its formula.

Momentum p is the product of mass and velocity: p = mv, and it has the same direction as velocity.

What is the SI unit of momentum?

Kilogram meter per second (kg·m/s).

What is the SI unit of force?

The Newton (N), defined as the force that produces an acceleration of 1 m/s^2 in a 1 kg mass.

State Newton's Third Law.

To every action there is an equal and opposite reaction; the two forces act on two different objects.

Give an everyday example of action–reaction forces.

A gun fires: the bullet is pushed forward, the gun experiences backward recoil.

How does friction influence motion on a surface?

Friction opposes motion and can balance pushing forces to prevent movement; when unbalanced, it can be overcome and motion occurs.

How is acceleration determined from force and mass?

Acceleration a = F/m; for a given force, lighter objects accelerate more; for a given mass, larger forces yield larger acceleration.

What is impulse and its relation to momentum?

Impulse equals the change in momentum and is the product of force and the time over which it acts: F·Δt = Δp.

Why did Galileo argue that uniform motion is possible without a continuing force on a frictionless plane?

Because there would be zero unbalanced external force; continuing motion would require no net force, though friction in practice prevents it.

How does inertia explain why a moving car causes you to lurch forward when braking suddenly?

Your body tends to continue moving due to inertia; braking applies backward force to the car, so the forward motion of your body feels like lurching forward; safety belts help by providing a forward reaction force.

What is the relationship between mass and inertia?

Mass is a measure of inertia; more mass means greater inertia.

What is the velocity-acceleration relation in a constant-mass scenario?

Acceleration a = (v − u)/t for uniform acceleration; more generally, a = Δv/Δt.

State the practical implications of collisions according to the laws of motion.

In a collision, equal and opposite forces act on two bodies; accelerations depend on each body’s mass (F = ma).

What is the unit for mass and its dimension?

Mass is measured in kilograms (kg).

Explain static friction in terms of balancing force.

Static friction adjusts to balance the applied force up to a maximum value, preventing motion until the threshold is exceeded.