Translational Motion II: Momentum and Impulse

Comprehensive practice flashcards covering translational motion, momentum, impulse, conservation laws, and types of collisions based on Grade 11 General Science lecture notes.

How is momentum ($p$) defined and calculated?

Momentum is a measure of an object's motion and its resistance to stopping, calculated as the product of mass ($m$) and velocity ($v$), represented by the formula $p = mv$.

What are the standard units for momentum, mass, and velocity as provided in the lesson?

Momentum is measured in $kg \times m/s$, mass in $kg$, and velocity in $m/s$.

Why is momentum considered a vector quantity?

Because velocity is a vector, momentum must also be a vector, meaning it has both magnitude and direction. Direction is critical when calculating total momentum.

What is the definition of Impulse ($J$)?

Impulse is the measure of a force applied over a specific duration ($\triangle t$), quantifying the push or pull that changes an object's motion. It is calculated as $J = F \triangle t$.

What units are used to measure impulse?

Impulse is measured in Newton-seconds ($N \times s$) or kilogram-meters per second ($kg \times m/s$).

Explain the Impulse-Momentum Theorem.

The theorem states that impulse is equal to the change in momentum. When a force acts over time, it causes acceleration, which changes the object's velocity and its resulting momentum.

What is the relationship between force and time for a fixed change in momentum?

Force and time are inversely related. A short impact time results in a high peak force (dangerous), while a long impact time results in a low peak force (safer).

In the case of stopping a $0.145\,kg$ baseball from $20\,m/s$, what is the required constant impulse?

The required constant impulse is $2.9\,N \times s$.

How do safety devices like Crumple Zones, Airbags, and Seatbelts reduce peak force during a collision?

They are designed to extend the impact time (collision duration), which reduces the peak force exerted on passengers.

What does the Law of Conservation of Momentum state for a closed and isolated system?

It states that the total momentum remains constant before and after an interaction (collision or explosion), provided no external forces are acting on the system.

How are collisions classified based on Kinetic Energy (KE)?

Collisions are classified as Elastic (KE is conserved), Inelastic (KE is lost to heat, sound, or deformation), and Perfectly Inelastic (maximum KE loss as objects stick together).

What are the characteristics of an Elastic Collision?

Both momentum and Kinetic Energy are conserved; objects involve hard, non-deforming surfaces and result in a clean bounce with no heat generation.

What happens to energy and objects in an Inelastic Collision?

Momentum is conserved but Kinetic Energy is not, as it transforms into heat, sound, or material deformation. Objects bounce but may be permanently dented.

What is the defining outcome of a Perfectly Inelastic Collision?

There is a maximum loss of Kinetic Energy and the objects stick together after impact, moving with a common final velocity ($v'$).

A $1500\,kg$ car moves east at $20\,m/s$. What is its momentum?

The momentum is $30,000\,kg \times m/s$ to the east.

If a soccer player kicks a $0.5\,kg$ ball with $10\,N$ of force over $0.2\,s$, what is the impulse?

The impulse is $2\,N \times s$ (or $2\,kg \times m/s$).

Two carts stick together after collision. Cart A ($2\,kg$) moves at $4\,m/s$ right and Cart B ($3\,kg$) is at rest. What is their shared final velocity?

The shared final velocity is $1.6\,m/s$ to the right.