Momentum & Newton’s Laws of Motion - Practice Flashcards

Question-and-answer flashcards covering mass, weight, momentum, and Newton’s laws of motion as described in the notes.

What is mass?

Mass is a measure of the amount of matter in an object and a property that resists changes in motion.

What is weight?

Weight is the force of gravity on a mass; it is W = mg, measured in newtons (N) and is a vector.

What is the SI unit of mass?

Kilogram (kg).

What is the SI unit of weight?

Newton (N).

In the formula W = mg, what does g represent?

g is the acceleration due to free fall (gravity), about 9.81 m/s^2 on Earth.

Do objects near Earth fall with the same acceleration in the absence of air resistance regardless of their mass?

Yes.

How does mass differ from weight when comparing Earth and the Moon?

Mass stays the same, weight changes with gravity; on the Moon weight is about 1/6 of Earth’s for the same mass (g_moon ≈ 1.63 N/kg).

What is linear momentum p defined as?

p = m × v (momentum is a vector).

Is momentum a scalar or a vector quantity?

Vector; it has both magnitude and direction.

What does Newton’s second law relate to motion when forces are not balanced?

A resultant force causes acceleration in the direction of the force; F = ma (and equivalently dp/dt ∝ F).

What is the formula for force in terms of momentum change?

F = Δp / Δt, the rate of change of momentum.

What is Δp in momentum problems?

Δp = pfinal − pinitial (the change in momentum).

What is Newton’s First Law of Motion?

A body at rest stays at rest or moves with constant velocity unless acted on by a resultant (net) force; equilibrium means net force is zero.

What is Newton’s Second Law of Motion?

A resultant force causes a change in the object's motion; F = ma (or equivalently Δp/Δt).

What is Newton’s Third Law of Motion?

For every action, there is an equal and opposite reaction; forces occur in equal and opposite pairs acting on different objects.

What happens to the force if the time of impact increases while the change in momentum stays the same?

The force decreases (F = Δp/Δt).