7.1 - distance and displacement

If two displacement vector add to yield a total displacement of zero, what do you know about the two displacements?

they are equal in length and opposite in direction

How is displacement combined?

Displacement are combined using vector addition

A person drives north 6 blocks, then turns west, and drives 6 blocks. The driver then turns south and drives 6 blocks. How could the driver have made the distance shorter while maintaining the same displacement?

by driving west 6 blocks from the starting point

Which distance can be most accurately measured with a ruler?

the width of a book

For what type of distances would you choose to make measurements in millimeters and what types of distances would you choose to make measurements in kilometers?

very small; very large

A ball is rolled uphill a distance of 5 meters before it slows, stops, and begins to roll back. The ball rolls downhill 9 meters before coming to rest against a tree. What is the magnitude of the ball's displacement?

4 meters

The SI unit for measuring length is the ________________.

meter

A spider is crawling up a wall. First it crawls 1 meter up, then 1 meter to the left, and then 1 meter down. What is the total displacement?

1 meter to the left

How is a frame of reference used to measure motion?

Motion can only be described in comparison to a frame of reference

Interpreting Graphics Figure 11-3B illustrates the displacement of an object moving in a plane. Explain what information is provided by arrows A and B.

Arrows A and B are vectors with magnitude (distance) and direction.

Displacement and velocity are examples of _____________ because they have both magnitude and direction.

vectors

What is the SI unit best used for measuring the height of a building?

meters

One kilometer equals 1000 meters. What does the prefix kilo-mean?

1000

What is a frame of reference?

A frame of reference is a set of objects that are not moving with respect to one another.

Calculating Using vector addition, calculate the distance traveled by the object and the displacement of the object represented by Figure 11-3B. (The second picture is 11-3B)

The object moved a total distance of 11 m + 5 m = 16 m. The object's displacement is 11 m - 5 m = 6 m to the right.

Displacement is distance combined with

direction

Examine the figure. If you were standing under the tree, which object would appear to be moving?

the airplane

A delivery truck driver's round-trip route from the warehouse takes her 3 km east, then 1 km north, then 3 km west, and then 1 km south. Which of the following statements is false?

After driving 3 km east, the magnitude of the distance and displacement are the same

Predicting Suppose vector B in Figure 11-3B had a length of 12 m (instead of 5 m). What would be the distance the object moved? What would be the magnitude of the object's displacement? (The second picture is 11-3B)

The distance would be 11 m + 12 m = 23 m. The displacement magnitude would be 11 m + (-12 m) = -1 m, or 1 m to the left.

A girl walks from her home to a friend's home 3 blocks north. She then walks 2 blocks east to the post office, 1 block north to the library, and 1 block east to the park. From the park, she walks 2 blocks west to the movie theater. After the movie, she walks 4 blocks south to the pet store. What is the girl's displacement from her starting point to the pet store? Where is the location of the pet store in relation to her home? Calculate the distance she walked in blocks.

The girl's displacement from home is 1 block east. The pet store is located 1 block east of her home. The girl walked a total distance of 13 blocks.

Displacement vectors of 3 m and 5 m in the same direction combine to make a displacement vector that is

8 m

The sum of two or more vectors is called the ______________.

resultant vector

Displacement vectors of 4 km south, 2 km north, 5 km south, and 5 km north combine to a total displacement of

2 km south

Motion is described with respect to a

frame of reference

______________ is the length of an object's actual path from starting point to an ending point.

distance

Distance is a measure of length. What information does displacement give in addition to distance?

direction

Why is it necessary to choose a single frame of reference when measuring motion?

the motion appears to be different in different frames of reference

A child rolls a ball 6 m across a room. The ball hits the wall and rolls halfway back toward the child. Using vector addition, calculate the ball's displacement.

3 m

________________ is the length of a straight line from the starting point to the ending point.

displacement

The direction and length of a straight line from the starting point to the ending point of an object's motions is _______________.

displacement

The motion of an object looks different to observers in different

frames of reference

A person walks 1 mile every day for exercise, leaving her front porch at 9:00 AM and returning to her front porch at 9:25 AM. What is the total displacement of her daily walk?

0

Should your directions to a friend for traveling from one city to another include displacements or distances?

Displacements will tell your friend how far and which directions to go: distances will only tell how far to go

A passenger in the rear seat of a car moving at a steady speed is at rest relative to

A passenger in the rear seat of a car moving at a steady speed is at rest relative to

From which frame of reference in the figure does the tree appear to be in motion?

the airplane