Laws of Motion and Friction Practice Flashcards

A collection of vocabulary-style flashcards covering key concepts from physics lecture notes on laws of motion, tension, centripetal force, and friction.

Magnitude of acceleration in a pulley system

The acceleration $a$ of two masses $m_1$ and $m_2$ ($m_1 > m_2$) connected by a string over a smooth pulley, given by $a = \frac{m_1 - m_2}{m_1 + m_2} g$.

Tension in the string (pulley system)

The force $T$ exerted by the string in a pulley system with masses $m_1$ and $m_2$, calculated as $T = \frac{2 m_1 m_2}{m_1 + m_2} g$.

Centripetal force

The force required to keep a body of mass $m$ moving with a speed $v$ in a circular path of radius $r$, given by $F = \frac{mv^{2}}{r}$ or $F = m r \omega^{2}$.

Centripetal acceleration

The acceleration of a particle moving with a constant speed $v$ along a circle of radius $r$, expressed as $a_c = \frac{v^{2}}{r}$.

Maximum speed on a rough horizontal road

The highest speed a car can safely maintain on a level curved road before sliding, given by $v_{max} = \sqrt{\mu_s r g}$, where $\mu_s$ is the coefficient of static friction.

Angle of banking

The angle $\theta$ at which a curved road is tilted such that the outer edge is higher than the inner edge, determined by the relation $\tan(\theta) = \frac{v^{2}}{rg}$ when friction is ignored.

Optimum speed

The ideal speed for a vehicle to negotiate a banked curve such that there is no reliance on friction, given by $v_{optimum} = \sqrt{rg \tan(\theta)}$.

Banking height

The height $h$ by which the outer edge of a road of width $b$ is raised, calculated as $h = b \tan(\theta)$.

Cause of friction

Interlocking of surface irregularities and atomic/molecular forces of attraction (cold welding) at points of actual contact between two bodies.

Coefficient of static friction ($\mu_s$)

The ratio of the force of limiting friction $f_l$ to the normal reaction $N$, defined as $\mu_s = \frac{f_l}{N}$.

Angle of repose ($\phi$)

The minimum angle of inclination of a plane such that a body placed on it just begins to slide down; numerically, $\mu_s = \tan(\phi)$.

Net acceleration on a rough inclined plane

The acceleration of a block sliding down a plane inclined at angle $\theta$, given by $a = g (\sin(\theta) - \mu_k \cos(\theta))$.

Maximum safe speed on a banked road

The maximum speed for a vehicle on a banked road considering friction, given by $v_{max} = \sqrt{rg \frac{\mu_s + \tan(\theta)}{1 - \mu_s \tan(\theta)}}$.

Concurrent forces

A set of forces acting simultaneously on a body such that their lines of action all meet at a common point.

Static friction

The self-adjusting opposing force that balances the applied force and keeps a body at rest before motion begins.

Limiting friction

The maximum value of static friction that occurs at the instant a body is about to start sliding.

Kinetic friction

The constant friction force that opposes the motion of a body as it slides over another surface, which is typically less than the limiting friction.