Distance and displacement introduction | One-dimensional motion | AP Physics 1 | Khan Academy

Summary

In this educational video, the instructor uses the example of a sheep's journey to explain the concepts of distance traveled and displacement. The sheep moves 10 km east, 5 km south, 10 km west, and then 5 km south again, totaling a 25 km journey. However, the final position is only 5 km south of the starting point, illustrating that displacement is the change in position, not the total path length.

Takeaways

• 🐏 The sheep's journey starts with it being hungry and seeking grass.
• 📏 The sheep travels 10 kilometers east initially.
• 🔄 After the first leg, the sheep makes a right turn and travels 5 kilometers south.
• 🔄 Another right turn leads to a 10-kilometer journey west.
• 🔢 The total distance traveled by the sheep is calculated as 25 kilometers.
• 🤔 There are two interpretations of how far the sheep has traveled: total distance and displacement.
• 🔍 Displacement is defined as the change in position from the starting point to the ending point.
• 🔼 The sheep's displacement is 5 kilometers south from its starting point.
• 📏 Distance traveled is the entire length of the journey and is always a non-negative value.
• 📍 Displacement is the change in position and includes direction, making it a vector quantity.

Q & A

What is the total distance the sheep traveled according to the video script?

The total distance the sheep traveled is 25 kilometers, calculated by adding 10 kilometers east, 5 kilometers south, another 10 kilometers west, and finally 5 kilometers south.

What is the net displacement of the sheep's position at the end of its journey?

The net displacement of the sheep's position is 5 kilometers south.

What is the difference between 'distance traveled' and 'displacement' as explained in the script?

Distance traveled refers to the total length of the journey or path taken, while displacement refers to the change in position from the starting point to the ending point.

Is the distance traveled by the sheep always positive?

Yes, the distance traveled is always positive as it represents the total length of the path taken, regardless of direction.

Can the displacement be negative according to the script?

No, displacement is not negative. It is a vector quantity that indicates the change in position, including both magnitude and direction.

What does the instructor mean by 'a little bit of a trick question' in the context of the sheep's journey?

The instructor refers to the possibility of two valid answers for how far the sheep traveled, depending on whether one is considering the total distance traveled or the displacement.

How does the instructor illustrate the sheep's journey in the script?

The instructor uses a drawing of a sheep and describes its movements: 10 kilometers east, 5 kilometers south, 10 kilometers west, and another 5 kilometers south.

What is the significance of the sheep taking a right turn at each stage of its journey?

The right turns indicate a change in direction for the sheep, which is necessary to understand both the total distance traveled and the final displacement.

What is the final position of the sheep relative to its starting point?

The final position of the sheep is 5 kilometers south of its starting point.

How does the instructor encourage viewers to engage with the content?

The instructor encourages viewers to pause the video and figure out the answers to the questions posed, promoting active participation and understanding.

What is the purpose of the instructor writing down the concepts of 'distance traveled' and 'displacement'?

The instructor writes down these concepts to emphasize their importance and to help viewers differentiate between the total path length and the change in position.