Question 1

Which of the following best defines a 'particle' in the context of physics motion diagrams?

Accepted Answer

An object that can be represented as a mass at a single point in space.

Question 2

A sled moves from position $$(x_3$, y_3$) = (15\ \mathrm{m}, 15\ \mathrm{m}) at$$ $$t_3 = 3$$\ \mathrm{s}$$ to $$($$x_4$$, $$y_4) = (25$$\ \mathrm{m}, 10\ \mathrm{m})$$ at t_4$ = 4\ \mathrm{s}. $$What is the displacement vector $$\Delta \vec{r}$$ from $$t_3 to$$ $$t_4$$?

Accepted Answer

$$\Delta \vec{r} = (10\ \mathrm{m}, -5\ \mathrm{m})$$

Question 3

Which of the following statements about displacement is correct?

Accepted Answer

Displacement is a vector that points from an object's initial position to its final position.

Question 4

Given vectors $$\vec{A}$$ and $$\vec{B}$$, which of the following correctly describes how to find $$\vec{A} + \vec{B}$$ using the graphical method?

Accepted Answer

Draw $$\vec{A}$$, place the tail of $$\vec{B} at $$the tip of $$\vec{A}$$, then draw the resultant from the tail of $$\vec{A} to $$the tip of $$\vec{B}.$$

Question 5

A runner completes a 400 m lap in 50 s. What is her average speed?

Accepted Answer

$$8.0\ \mathrm{m/s}$$

Question 6

Which of the following is true about average velocity?

Accepted Answer

Average velocity is a vector quantity that depends on displacement and time interval.

Question 7

A car accelerates from rest to $$30\ \mathrm{m/s} in$$ $$10\ \mathrm{s}. $$What is its average acceleration?

Accepted Answer

$$3.0\ \mathrm{m/s^2$}$$

Question 8

Which of the following best describes how to find the acceleration vector between two velocity vectors $$\vec{v}_i$$ and $$\vec{v}_f$$?

Accepted Answer

Draw $$\vec{v}_f$$, then draw $$-\vec{v}_i at $$the tip of $$\vec{v}_f$$, and the vector from the tail of $$\vec{v}_i to $$the tip of $$\vec{v}_f is$$ $$\Delta \vec{v}.$$

Question 9

A stopwatch is used to measure a time interval. If an object moves from $$t_i = 2\ \mathrm{s} to$$ $$t_f = 7\ \mathrm{s}$$, what is the time interval $$\Delta t$$?

Accepted Answer

$$5\ \mathrm{s}$$

Question 10

In a motion diagram, what does the length of a velocity vector represent?

Accepted Answer

The speed of the object at that instant.

Question 11

A car accelerates up a $$20^\circ$$ hill from rest. Which of the following best describes the motion diagram for the car?

Accepted Answer

The dots are spaced farther apart as the car speeds up, and the velocity vectors increase in length along the $$20^\circ$$ incline.

Question 12

Which of the following is true about the acceleration vector in a motion diagram?

Accepted Answer

It is constructed from two velocity vectors and is placed at the midpoint between them.

Question 13

A tortoise and a hare are racing. The hare's velocity vectors are longer than the tortoise's in a motion diagram. What does this indicate?

Accepted Answer

The hare is moving faster than the tortoise.

Question 14

If a runner's displacement is zero after a race, what can be said about her average velocity and average speed?

Accepted Answer

Average velocity is zero, but average speed is not zero.

Question 15

Which of the following is a correct statement about time intervals in physics?

Accepted Answer

The time interval $$\Delta t is $$calculated as $$t_f - t_i.$$

Question 16

A cyclist travels 100 m north, then 100 m east. What is the magnitude of the cyclist's displacement?

Accepted Answer

$$\sqrt{100^2$ + 100^2$} = 141\ \mathrm{m}$$

Question 17

Which of the following is NOT a step in constructing a complete motion diagram?

Accepted Answer

Drawing the object's path as a continuous line only, without dots or vectors.

Concepts of Motion: Particles, Motion Diagrams, and Vectors

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