Glossary
Acceleration (a)
The rate at which an object's velocity changes over time, a vector quantity indicating both magnitude and direction.
Example:
A car pressing the gas pedal experiences positive acceleration, while a car braking experiences negative acceleration (deceleration).
Angular Tension
The force exerted by a string or cable when it is pulling on an object at an angle, requiring resolution into horizontal and vertical components.
Example:
When a chandelier is hung by two cables, the angular tension in each cable must be calculated to ensure it can support the weight.
Apparent Weight
The perceived weight of an object, which is determined by the normal force acting on it, and can differ from its true weight due to acceleration.
Example:
In an elevator accelerating upwards, you feel heavier because your apparent weight increases.
Center of Mass
The 'average' position of all the mass in a system, whose motion describes the overall movement of the system.
Example:
When a baseball bat is thrown, its complex tumbling motion can be simplified by tracking the smooth parabolic path of its center of mass.
Displacement (Δx)
The change in an object's position, a vector quantity indicating both magnitude and direction from the initial to the final point.
Example:
If you walk 5 meters east and then 5 meters west, your total distance traveled is 10m, but your displacement is 0m.
Final Velocity (Vf)
The velocity of an object at the end of a specific time interval or motion.
Example:
After accelerating down a ramp, the skateboarder's final velocity just before hitting the ground was 15 m/s.
Free Fall
The motion of an object solely under the influence of gravity, where the only force acting on it is its weight.
Example:
An object dropped from a height, neglecting air resistance, is in free fall.
Free-Body Diagram (FBD)
A visual representation that isolates an object and shows all external forces acting upon it as vectors.
Example:
Before solving a problem involving a block on an inclined plane, drawing a free-body diagram helps identify gravitational, normal, and frictional forces.
Initial Velocity (Vo)
The velocity of an object at the beginning of a specific time interval or motion.
Example:
A car starting from rest has an initial velocity of 0 m/s.
Kinematic Equations
A set of four equations that describe the motion of objects with constant acceleration, relating displacement, velocity, acceleration, and time.
Example:
To find out how far a dropped ball falls in 2 seconds, you would use one of the kinematic equations.
Newton's Second Law
States that the net force acting on an object is equal to the product of its mass and acceleration (F=ma).
Example:
Pushing a small toy car requires less force to achieve the same acceleration than pushing a large truck, illustrating Newton's Second Law.
Normal Force (Fn)
The force exerted by a surface that supports an object, acting perpendicular to the surface.
Example:
When you stand on the ground, the ground exerts an upward normal force on you, preventing you from falling through it.
Time (t)
The duration over which a physical process or motion occurs.
Example:
It took a time of 3 seconds for the apple to fall from the tree to the ground.
True Weight (mg)
The actual gravitational force acting on an object, calculated as its mass multiplied by the acceleration due to gravity.
Example:
An astronaut's true weight on the Moon is less than on Earth because the Moon's gravity is weaker, even though their mass remains the same.