Simple Machines, Forces, and Motion Practice Flashcards

Comprehensive vocabulary flashcards covering simple machines, the nature of forces, everyday forces including Hooke's Law, and the fundamentals of motion and speed based on the provided lecture notes.

Machines

Devices built by human beings to change and even multiply forces.

Simple machine

A mechanical device that changes the magnitude or direction of a force.

Lever

A simple machine consisting of a rigid bar which rotates freely on a fixed point called a fulcrum.

Effort (F)

The force we apply to a machine to move or lift a load.

Load (R)

The force we want to overcome using a simple machine.

Law of the lever

The principle stating that the product of the beam ($B$) and the force is the same for both the effort and the load, expressed as $F imes B_F = R imes B_R$.

First-class lever

A lever where the fulcrum is located between the effort and the load, such as scissors or pliers.

Second-class lever

A lever where the load is between the effort and the fulcrum, such as a wheelbarrow or nutcracker.

Third-class lever

A lever where the effort is between the load and the fulcrum, such as a stapler or tweezers.

Inclined plane

A flat surface set at an angle to the horizontal ground used to raise a load with less force by increasing the distance travelled.

Pulley

A simple machine based on the wheel and axle that changes the direction of a force or multiplies it when several are combined.

Block and tackle

A machine used to lift and lower heavy loads using a chain and a combination of pulleys.

Wedge

A triangular tool, technically a double inclined plane, used to split materials, hold objects in place, or fill gaps.

Force

A cause that affects either a change in the state of motion of a body or a deformation of the body.

Newton (N)

The SI unit used to measure the magnitude of a force.

Vector

A line segment with an arrow used to represent force, indicating its direction, sense, and magnitude.

Elastic body

A body that recovers its original shape when the deforming force stops acting on it.

Plastic body

A body that remains deformed after the force stops acting on it, such as clay or plasticine.

Rigid body

A body that does not appear to deform under the action of a force because the deformation is too small to be observed.

Resultant force

The single force obtained by adding the magnitudes and directions of all individual forces acting on a body.

Contact force

A type of force exerted when one body physically touches another, such as friction or tension.

Force at a distance

A force applied to an object without physical contact, such as magnetic attraction or gravity.

Friction force

A contact force exerted by a surface that works against objects in motion and does not depend on the object's speed.

Air resistance

A friction force that slows objects moving through the air, which increases with the speed and aerodynamics of the object.

Weight (W)

The force of attraction a planet exerts on an object's mass ($m$), calculated on Earth using gravity $g = 9.8\,N/kg$ as $W = m imes g$.

Normal force

A contact force exerted by a surface perpendicular to the objects resting on it, preventing them from passing through.

Tension

The force that strings, ropes, or cables exert on objects tied to one end.

Hooke's Law

A law stating that the deformation ($\Delta l$) of an elastic material is proportional to the force ($k$) exerted on it, expressed as $F = k imes \Delta l$.

Spring constant (k)

A value depending on the characteristics of an elastic material, expressed in newtons per metre ($N/m$).

Dynamometer

An instrument used for measuring force, such as weight, utilizing the properties of springs.

Reference system

A static point, known as the origin, used to locate bodies and describe their movement.

Trajectory

The line formed by joining the successive positions a body occupies during its motion.

Distance travelled (d)

The distance measured along the trajectory between the initial and final positions, calculated as $d = s - s_0$.

Average speed ($v_a$)

The space travelled divided by the time interval, expressed in SI units as metres per second ($m/s$).

Instantaneous speed

The speed of a body at any given moment, often shown by a vehicle's speedometer.

Velocity

A vector quantity that indicates the rate of motion in a straight line, requiring both a value and a direction.

Uniform motion

Movement where the speed is constant and acceleration is zero, resulting in a distance travelled that is directly proportional to time.