GERAK LURUS BERUBAH BERATURAN (GLBB) - GERAK LURUS (FISIKA SMA)

Summary

This video explains Uniformly Accelerated Linear Motion (GLBB) in a clear, step-by-step way for students learning basic physics. It covers the definition of GLBB, emphasizing that velocity changes uniformly due to constant acceleration, which can be positive (acceleration) or negative (deceleration). The instructor explains acceleration as the change in velocity per unit time and introduces key GLBB formulas for velocity, distance, and acceleration. Direction and sign conventions are highlighted, along with interpretations of velocity–time and distance–time graphs. The lesson is reinforced through multiple worked examples, including vehicles accelerating, braking, stopping distances, and analyzing motion from graphs, helping viewers apply concepts logically and correctly.

Takeaways

• 😀 GLBB (Gerak Lurus Berubah Beraturan) refers to motion where velocity changes in a uniform manner, meaning acceleration is constant.
• 😀 Acceleration (a) in GLBB is the rate of change of velocity per unit time, and it is expressed in meters per second squared (m/s²).
• 😀 Positive acceleration means the velocity is increasing (speeding up), while negative acceleration (deceleration) means the velocity is decreasing (slowing down).
• 😀 There are various formulas for GLBB, including those for final velocity (VT), average velocity, and distance traveled.
• 😀 The formula for final velocity is VT = v0 + a * t, where v0 is initial velocity, a is acceleration, and t is time.
• 😀 To calculate distance (s), you can use the formula: s = v0 * t + 1/2 * a * t², or alternatively, s = average velocity * time.
• 😀 If time is unknown in a GLBB problem, use the formula VT² = v0² + 2 * a * s to find distance.
• 😀 In GLBB motion, when acceleration is positive, the object speeds up; when acceleration is negative, the object slows down.
• 😀 When graphing VT (velocity vs time) and ST (distance vs time), GLBB shows a linear VT graph for accelerating motion and a curve for distance, where the area under the graph gives the distance traveled.
• 😀 For decelerating GLBB, the VT graph slopes downward, indicating a decrease in velocity, while the ST graph curves downward.
• 😀 Key to solving GLBB problems is understanding the vector nature of acceleration, where direction matters: upwards and to the right are positive, downwards and to the left are negative.

Q & A

What is GLBB (Uniformly Accelerated Linear Motion)?

GLBB is a type of straight-line motion in which an object’s velocity changes at a constant rate, meaning the object experiences constant acceleration.

How does GLBB differ from GLB (Uniform Linear Motion)?

In GLB, the velocity is constant and acceleration is zero, while in GLBB, the velocity changes over time due to a constant acceleration.

What is acceleration and how is it defined in physics?

Acceleration is the rate of change of velocity with respect to time. It is defined as the change in velocity divided by the time interval.

What is the SI unit of acceleration?

The SI unit of acceleration is meters per second squared (m/s²).

What does it mean when acceleration is negative?

Negative acceleration indicates deceleration (or retardation), meaning the object’s speed is decreasing over time when moving in the positive direction.

What are the main equations used in GLBB?

The main equations are: v = v₀ + at, s = v₀t + ½at², v² = v₀² + 2as, and average velocity v̄ = (v₀ + v)/2.

How can distance traveled be determined from a velocity–time graph?

The distance traveled is equal to the area under the velocity–time (v–t) graph.

What does the slope of a velocity–time graph represent in GLBB?

The slope of a velocity–time graph represents acceleration. A steeper slope indicates a greater acceleration.

How does the position–time (s–t) graph look for GLBB?

For GLBB, the position–time graph is a curve (parabola), showing that position changes non-linearly with time due to constant acceleration.

How do direction and sign conventions affect calculations in GLBB?

Because acceleration and velocity are vector quantities, direction matters. Motions upward or to the right are usually taken as positive, while downward or to the left are taken as negative.

In the braking car example, why does the car hit the person?

The car requires 40 meters to come to a complete stop, while the person is only 15 meters away, so the stopping distance is longer than the available distance.

How can multiple types of motion appear in one velocity–time graph?

Different segments of a v–t graph can represent different motions, such as accelerated motion (slanted line), constant velocity motion (horizontal line), and decelerated motion (downward slanted line).