Linear Momentum

Four topics on motion's other measure. Linear momentum as the vector that tracks how much motion an object carries, impulse as the force-times-time delivery that changes it, conservation of momentum as the bookkeeping rule when no net external force acts, and elastic and inelastic collisions as the testbed where momentum is always conserved but kinetic energy may not be.

Topics

4.1

Linear Momentum

Change in Momentum and Impulse

Conservation of Linear Momentum

Elastic and Inelastic Collisions

Lesson

Diag

locked

Equations For every problem in this unit

Linear momentum

$\vec{p} = m \vec{v}$

Newton's second law, momentum form

$\vec{F}_{\text{net}} = \dfrac{\Delta \vec{p}}{\Delta t} = m \dfrac{\Delta \vec{v}}{\Delta t} = m \vec{a}$

Impulse-momentum theorem

$\vec{J} = \vec{F}_{\text{avg}}\, \Delta t = \Delta \vec{p}$

Velocity of center of mass

$\vec{v}_{\text{cm}} = \dfrac{\sum \vec{p}_i}{\sum m_i} = \dfrac{\sum m_i \vec{v}_i}{\sum m_i}$

Pythagorean

$a^2 + b^2 = c^2$

Sine, opp / hyp

$\sin\theta = \dfrac{a}{c}$

Cosine, adj / hyp

$\cos\theta = \dfrac{b}{c}$

Tangent, opp / adj

$\tan\theta = \dfrac{a}{b}$

Unit 4 tools

Challenge bank

1 / 60

60 open-ended problems.

Read the question, work it out, then flip the card to compare your reasoning to the worked solution. Mark each card so you can return to the ones that still bite.

Question

Tap card to reveal explanation

Worked solution

Tap card to return to question

Cumulative assessment

Test the unit.

Twenty mixed items pulled from across all 4 topics. Identifies which misconceptions still bite when you cannot see which topic the question came from.