General Science Exam Reviewer: Rotational Motion, Torque, Ergonomics, and Machines

A comprehensive set of 60 vocabulary flashcards covering rotational motion, torque, ergonomics, and simple/compound machines based on general science lecture notes.

Rotational Motion

The motion of a body turning about an axis where each particle or point of the body moves along a circular path.

Axis

The imaginary or fixed line around which an object rotates.

Rotation

The turning motion of an object around an axis.

Circular path

The path followed by individual points or particles on a rotating object.

Linear Motion

Motion characterized by an object moving from one place to another rather than turning around an axis.

Angular displacement ($\theta$)

A measure of how much an object has rotated, typically measured in degrees, revolutions, or radians.

Angular velocity ($\omega$)

A measure of how fast an object is rotating, defined as the change in angular displacement over time.

Angular acceleration ($\alpha$)

A measure of how quickly the angular velocity of an object changes over time.

Revolution

A unit of angular displacement where $1\text{ revolution}=360^\circ=2\pi\text{ rad}$.

Radian ($\text{rad}$)

A unit of angular displacement where $1\text{ rev} \approx 6.28\text{ rad}$.

$$180^\circ$$

An angular measurement equivalent to $\pi\text{ rad}$.

$$90^\circ$$

An angular measurement equivalent to $\frac{\pi}{2}\text{ rad}$.

Linear displacement ($d$)

The length of the arc traveled by a point on a rotating object, calculated using the relationship $d=r\theta$.

Radius ($r$)

The distance from the axis of rotation to a specific point on a rotating body.

$$rad/s$$

The standard unit used to measure angular velocity ($\omega$).

$$rad/s^2$$

The standard unit used to measure angular acceleration ($\alpha$).

$$\omega_f = \omega_i + \alpha t$$

The rotational kinematics formula used to calculate final angular velocity.

$$\theta = \omega_i t + \frac{1}{2}\alpha t^2$$

The rotational kinematics formula used to find angular displacement when time is provided.

$$\omega_f^2 = \omega_i^2 + 2\alpha\theta$$

The rotational kinematics formula used to solve problems where time is not given.

$$\theta = \frac{\omega_i + \omega_f}{2}t$$

The rotational kinematics formula used to calculate angular displacement using average angular velocity and time.

GRESA

An acronym representing the problem-solving steps: Given, Required, Equation, Solution, and Answer.

Torque ($\tau$)

The turning effect or "twist" factor of a force that causes angular acceleration.

Newton-meter ($N \cdot m$)

The standard unit of measurement for torque.

$$\tau = rF$$

The formula for torque when a force is applied perpendicular to the lever arm.

$$\tau = rF\sin(\theta)$$

The general formula for torque, where $\theta$ is the angle between the force and the lever arm.

Lever arm ($r$)

The distance from the axis or pivot point to the location where force is applied.

Pivot

The axis or fixed point around which an object turns when torque is applied.

Maximum Torque

Produced when a force is applied perfectly perpendicular ($90^\circ$) to the lever arm.

Zero Torque

Occurs when a force is applied along the lever arm ($0^\circ$) because $\sin(0^\circ)=0$.

Ergonomics

The science of designing environments, products, and systems to fit the people who use them.

Physical Ergonomics

A field focused on reducing unnecessary stress or force on the body to improve safety and effectiveness.

Goal of Ergonomics

To improve both human well-being and system performance by making the task fit the person.

Natural joint position

An ergonomic principle of keeping joints, such as wrists, straight rather than awkwardly angled.

Wide Base of Support (BOS)

Placing feet approximately shoulder-width apart to create a more stable base and better balance.

Proximity

The principle of getting as close to an object as possible when lifting to reduce the moment arm.

Moment arm

The horizontal distance from the body to an object that, when increased, requires more force from the lower back.

Spinal flexion

The rounding of the back during lifting, which should be avoided to prevent injury.

Hip hinge

A movement where rotation occurs at the hips rather than the spine to maintain ergonomic safety.

Large muscle groups

Powerful muscles like the glutes, quadriceps, and hamstrings that should be used during lifting.

Glutes

One of the large muscle groups used in ergonomic lifting movements.

Quadriceps

One of the large muscle groups situated in the legs used for safe lifting.

Hamstrings

One of the large muscle groups utilized when performing proper hip hinge movements.

Micro-traumas

Small injuries to joints that can be prevented by minimizing unnecessary force during tasks.

Simple Machine

A basic mechanical device that changes the magnitude or direction of a force to perform work.

Lever

A rigid bar that pivots around a fixed point called a fulcrum.

Fulcrum

The specific point around which a lever rotates or pivots.

Wheel and Axle

A simple machine consisting of a wheel attached to a shaft or axle that move together.

Pulley

A grooved wheel around which a rope, belt, or chain passes to change the magnitude or direction of force.

Inclined Plane

A flat surface set at an angle, such as a ramp, used to lift objects by pushing or pulling them.

Ramp

The most common example of an inclined plane simple machine.

Wedge

A moving inclined plane that tapers to a thin edge used for splitting, cutting, or tightening.

Screw

A simple machine consisting of an inclined plane wrapped around a cylinder to form a path and pitch.

Compound Machine

A mechanical device consisting of two or more simple machines working together.

Bicycle

A common example of a compound machine that involves multiple simple-machine components.

Scissors

A compound machine that combines a lever-like action with wedge-shaped blades.

Magnitude of force

One of the two primary properties changed by a simple machine to make work easier.

Direction of force

One of the two primary properties changed by a simple machine, such as by using a pulley.

$$2\pi\text{ rad}$$

The value in radians equivalent to one full revolution or $360^\circ$.

Axle

The shaft attached to a wheel in a wheel and axle system that acts as a lever arm.

Axe

A specific example of a wedge used for splitting objects.