If an object moves relative to a reference frame—for example, if a professor moves to the right relative to a whiteboard, or a passenger moves toward the rear of an airplane—then the object's position changes. This change in position is known as displacement. What is the formula for distance in physics? Rate and speed are similar since they both represent some distance per unit time like miles per hour or kilometers per hour.
What are the similarities and differences between distance and displacement? Distance refers to the amount of space between two points, measured along the actual path, linking them. Displacement refers to the amount of space between the two points, measured along the minimum path linking them. Is force a vector? A force is a vector quantity.
As learned in an earlier unit, a vector quantity is a quantity that has both magnitude and direction. To fully describe the force acting upon an object, you must describe both the magnitude size or numerical value and the direction. How do u calculate distance? The positions of the words in the triangle show where they need to go in the equations.
To find the speed, distance is over time in the triangle, so speed is distance divided by time. To find distance, speed is beside time, so distance is speed multiplied by time. Is acceleration a scalar or vector? Acceleration is a vector quantity because it has both magnitude and direction. In determining the overall distance traveled by the physics teachers, the various directions of motion can be ignored.
Now consider another example. The diagram below shows the position of a cross-country skier at various times. At each of the indicated times, the skier turns around and reverses the direction of travel. In other words, the skier moves from A to B to C to D. Use the diagram to determine the resulting displacement and the distance traveled by the skier during these three minutes.
Then click the button to see the answer. As a final example, consider a football coach pacing back and forth along the sidelines. The diagram below shows several of coach's positions at various times. At each marked position, the coach makes a "U-turn" and moves in the opposite direction. Galileo came to an amazing conclusion. Only by looking at each other can a person in the ship or a person on shore describe the motion of one relative to the other.
In addition, their descriptions of motion would be identical. A person inside the ship would describe the person on the land as moving past the ship. The person on shore would describe the ship and the person inside it as moving past. Galileo realized that observers moving at a constant speed and direction relative to each other describe motion in the same way.
Galileo had discovered that a description of motion is only meaningful if you specify a reference frame. Before your parent drives you to school, the car is sitting in your driveway. Your driveway is the starting position for the car. When you reach your high school, the car has changed position. Its new position is your school. Physicists use variables to represent terms. We will use a subscript to differentiate between the initial position, d 0 , and the final position, d f.
In addition, vectors, which we will discuss later, will be in bold or will have an arrow above the variable. Scalars will be italicized. In some books, x or s is used instead of d to describe position. In d 0 , said d naught , the subscript 0 stands for initial. When we begin to talk about two-dimensional motion, sometimes other subscripts will be used to describe horizontal position, d x , or vertical position, d y. So, you might see references to d 0x and d fy. Now imagine driving from your house to a friend's house located several kilometers away.
How far would you drive? The distance an object moves is the length of the path between its initial position and its final position. The distance you drive to your friend's house depends on your path. As shown in Figure 2. The distance you drive to your friend's house is probably longer than the straight line between the two houses. We often want to be more precise when we talk about position.
For instance, if it is a five kilometer drive to school, the distance traveled is 5 kilometers. After dropping you off at school and driving back home, your parent will have traveled a total distance of 10 kilometers. The car and your parent will end up in the same starting position in space. Help students learn the difference between distance and displacement by showing examples of motion.
Ask—Which motion showed displacement? Which showed distance? Point out that the first motion shows displacement, and the second shows distance along a path. In both cases, the starting and ending points were the same. Emphasize that although initial position is often zero, motion can start from any position relative to a starting point.
As students watch, place a small car at the zero mark. Slowly move the car to students' right a short distance and ask students what its displacement is.
Then move the car to the left of the zero mark. Point out that the car now has a negative displacement. Students will learn more about vectors and scalars later when they study two-dimensional motion. For now, it is sufficient to introduce the terms and let students know that a vector includes information about direction. Have them use the arrows to identify the magnitude number or length of arrows and direction of displacement.
Emphasize that distance cannot be represented by arrows because distance does not include direction. In this activity you will compare distance and displacement. Which term is more useful when making measurements? Choose a room that is large enough for all students to walk unobstructed.
Make sure the total path traveled is short enough that students can walk back and forth across it multiple times during the course of a song. Have them measure the distance between the two points and come to a consensus. When students measure their displacement, make sure that they measure forward from the direction they marked as the starting position. After they have completed the lab, have them discuss their results. If you are describing only your drive to school, then the distance traveled and the displacement are the same—5 kilometers.
When you are describing the entire round trip, distance and displacement are different. When you describe distance, you only include the magnitude , the size or amount, of the distance traveled.
However, when you describe the displacement, you take into account both the magnitude of the change in position and the direction of movement. In our previous example, the car travels a total of 10 kilometers, but it drives five of those kilometers forward toward school and five of those kilometers back in the opposite direction.
A quantity, such as distance, that has magnitude i. A quantity, such as displacement, that has both magnitude and direction is called a vector. Create Account. Already Have an Account? What is difference between distance and displacement? Class 9 Question. Answer to Question. Ankita Sep 16, Upvote 6. Kritika Jain Apr 17, Distance is the measure of area which is between two points which is the point of origin or the starting point and ending point of a location.
Displacement is actually the distance a person is away from its actual point or the starting point. Distance is a scalar quantity 2.
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