chapter 3 physics vocab + practice questions

Alice starts at (4, 4) m and moves displacements of d1 = (-4,8) m, d2 = (6,16) m, and d3 = (-3,-13) m. What is Alice's total displacement? (hint: add up the x- and y-components separately)

(-1, 11) m

Thomas starts at the position (-3, -3) m in the x-y plane and undergoes the following displacements: d1 = (-4,1) m, d2 = (2,1) m, and d3 = (3,-3) m. What is Thomas's final position?

(-2, -4)

Starting at (-4, -5) cm, a toy car has the following displacements: (1, -8) cm, and (-4, 1) cm. What is the final position of the car?

(-7, -10)

An aircraft takes off from Austin, TX, flies 380 km west, lands, and then takes off again and flies 290 km east. If you define east as positive and west as negative, what is the plane's final position relative to Austin?

-90 km

Andoni gets into an elevator and travels 55 m straight up in a time of 18 s. He then travels the opposite direction, straight down, for 22 m in a time of 27 s. What is his average velocity over the 45 s period?

.73 m/s

Ryan moves to the right with a positive velocity of 5 m/s for 1 s, then to the left with a negative velocity of −5 m/s for 1 s. What is Ryan's displacement after 2 s?

0 m

Kim runs at a constant velocity of 3 m/s for 5 s. She then stops to rest for 5 s. What is her average velocity over the whole 10 s?

1.5 m/s

Two motorcycles approach each other on the same road. One has a constant velocity of +19 m/s and the other has a constant velocity of −11 m/s. If at time t = 0 s they are 570 m apart, how long would it be before they meet each other.

19 sec.

Jake travels at a constant speed of 50 km/hr toward his destination 250 km away. How long does it take him to arrive?

5 hours

A car starts at a position of 4 km and moves to a final position of 9 km. What is the total distance traveled by the car?

5 km

What is the average speed of a car that moves 900 m in 11 s?

82 m/s

Describe in one sentence how the word speed relates to something you know. Your answer must use the word in its correct meaning for physics.

Examples: My brother's car was moving at a speed of 55 mph yesterday. The maximum legal speed on my street is 30 mph

Use the word position in a sentence describing an experience you had. You must use the word so that its meaning is similar to what position means in physics.

Examples: The queen on a chess board starts at a position in the first row on the fourth square from the left. Highway markers are placed at positions 0.1 miles apart on many roads.

A problem contains 9 unknown values and 4 independent equations. Can this problem be solved to find a unique solution?

No, because there are more unknown variables than equations.

displacement

a change in position. can be positive or negative like position

origin

a fixed reference point that you choose

The term vector is best described by which of the following?

a quantity that has a magnitude and a direction

inertial reference frame

a reference frame in which the velocity is constant in both speed and direction

vector

a type of variable that includes information (usually mathematic) about direction, as well as size

position

a unique location in space with reference to an origin and a coordinate system.

In one dimension, positions and displacements can be positive, negative, or zero. a. What is the difference between a negative position and a negative displacement? b. Is it possible to undergo a negative displacement and end up at a positive position?

a. A negative position is any location to the left of the origin. A negative displacement is any change in position that involves moving in the negative direction. b. Yes, it is possible to undergo a negative displacement and end up at a positive location. For example, an object at position +8.0 m can undergo a displacement d = −2.0 m and end up at the position +6.0 m.

Classify each of the following as a distance or a displacement: a. Jodie sat 20 ft from the teacher's desk. b. Maurice drove his car a quarter-mile north of the train station. c. Yasmin hiked 6 km through the San Gabriel Wilderness. d.Ali kicked the ball 40 yards away.

a. Distance: No direction is given. b. Displacement: A direction ("north") is specified c. Distance: No direction is given. d. Distance: No direction is given.

displacements in two dimensions are written as...

coordinate points (ex: displacement of (3,1) means it traveled right 3, up 1)

Is density an example of a vector or scalar quantity?

density is an example of a scalar quantity

scalar

does not depend on direction and can be completely specified with a single value (ex: distance, mass, and temp)

On a position versus time graph, what type of motion does a line segment with a negative linear slope represent?

moving with a constant negative velocity

reference frame

something used that is at rest to determine how far your object has moved

magnitude

the "length" of a vector and is independent of its direction (ex: displacement of +10 m and -10 m both have magnitude of 10 m)

average velocity

the total displacement (or distance) traveled divided by total time

coordinates

values that specify position relative to the origin

displacement is a...

vector, while distance is not

instantaneous velocity

velocity of an object at any particular moment (may be faster or slower than the average)