Soal 1 | Kisi-kisi UAS Fisdas 1B 2024

Summary

In this tutorial, J. Saputra, an alumni of Teknik Fisika, explains the concept of torque (momen gaya) in rotational dynamics. The video covers how torque depends on the force applied and the distance from the axis of rotation, illustrated through practical examples like opening a door and using a wrench. Key topics include the conditions for calculating torque, the effect of force and radius, and common physics problems related to rotational motion. This tutorial is especially helpful for students preparing for exams like UAS FDA 1B, offering clear explanations and real-world applications.

Takeaways

• 😀 Assalamualaikum and welcome to the channel, where we are discussing an online tutorial for the UAS FDA 1B exam.
• 😀 The tutorial will cover 15 questions from the exam, ranging in difficulty from easy to hard, and will include essay-style questions.
• 😀 The speaker introduces themselves as J. Saputra, an alumni of the physics engineering program, and mentions the availability of Instagram updates for more content.
• 😀 The first topic discussed is rotational dynamics, specifically the concept of torque (moment of force) and its relationship with force and distance from a pivot point.
• 😀 Torque is the effectiveness of a force to rotate an object around a specific axis, and it is calculated as force multiplied by the perpendicular distance to the axis.
• 😀 The example given explains how torque is affected by both the magnitude of the force and the distance from the pivot, showing that larger force and distance result in greater torque.
• 😀 An illustration comparing two doors shows that a force applied at the edge of a door (greater distance from the pivot) results in faster rotation and greater torque.
• 😀 The speaker emphasizes that torque is larger when the distance from the pivot is greater, making it easier to rotate an object.
• 😀 In the problem-solving section, it is explained that a large force can result in a small torque if the distance (r) is small, or if the force is not applied perpendicularly.
• 😀 The tutorial also answers whether a small force can generate a large torque, explaining that increasing the distance (r) can compensate for the small force to produce a larger torque.
• 😀 The second example involves using a wrench to tighten a bolt, demonstrating the formula for calculating torque: Torque = Force × Distance (where both force and distance are perpendicular).

Q & A

What is torque (momen gaya) in physics?

Torque, also known as moment of force, is a measure of the effectiveness of a force applied to rotate an object about a specific pivot point or axis. It is calculated as the product of the applied force and the distance from the pivot point to the line of action of the force.

What is the formula for calculating torque?

The formula for calculating torque is: Torque (τ) = Force (F) × Distance (r). If the force is applied at an angle, the formula becomes: Torque (τ) = F × r × sin(θ), where θ is the angle between the force vector and the line of action.

How does the angle of application affect the torque?

The torque is maximized when the force is applied perpendicular to the lever arm (i.e., at a 90° angle). At this angle, the sin(90°) = 1, giving the largest possible torque. If the angle is less than 90°, the torque decreases as the force component along the line of action decreases.

In what way does the distance (r) from the pivot point affect the torque?

The torque increases with the distance from the pivot point. A larger distance means that the force has more leverage, which results in a larger torque. This is why applying force farther from the pivot is more effective for rotating objects.

Can a large force produce a small torque? If so, how?

Yes, a large force can produce a small torque if the distance from the pivot point (r) is small. Torque depends on both force and distance, so if the distance is very small, the torque will remain small even if the force is large.

How can a small force generate a large torque?

A small force can generate a large torque if the distance from the pivot point is large. The torque increases as the distance (r) increases, so applying a small force at a large distance from the pivot can result in a significant torque.

What example from daily life demonstrates the concept of torque?

An example is opening a door. If you apply force at the edge of the door, you generate a large torque, causing the door to open more easily. In contrast, if you apply the same force near the hinge, the torque is smaller, making it harder to open the door.

What happens if the applied force is not perpendicular to the lever arm?

If the force is not applied perpendicular to the lever arm, the torque will be reduced. In such cases, the force must be decomposed into two components (along the x and y axes), and only the component perpendicular to the lever arm contributes to the torque.

What is the relationship between torque and rotational acceleration?

Torque is directly related to rotational acceleration according to Newton's second law for rotation: Torque (τ) = Moment of inertia (I) × Angular acceleration (α). This means that a larger torque will cause greater rotational acceleration if the moment of inertia is constant.

How do the concepts of force, distance, and torque apply to mechanical tools like a wrench?

When using a wrench to tighten a bolt, the length of the wrench acts as the distance (r) from the pivot (the bolt). A force applied at the end of the wrench creates a torque that makes it easier to turn the bolt. The longer the wrench, the greater the torque produced by the same applied force.