Question 1

Which of the following best describes the particle model of motion?

Accepted Answer

It models an object as if all its mass were concentrated at a single point, ignoring its size and shape.

Question 2

A car moves along a straight road. Its position at $$t_0 = 0$ s is x_0$ = 10 m$$, and at $$t_1 = 5$ s it is x_1$ = 40 m. $$What is the car's displacement?

Accepted Answer

$$30 m$$

Question 3

Which of the following quantities is a vector?

Accepted Answer

Displacement

Question 4

A ball is dropped from a height and falls straight down. Which statement about its acceleration is correct?

Accepted Answer

The acceleration points downward throughout the motion.

Question 5

A student walks 30 m east, then 40 m west. What is her total distance traveled and her displacement?

Accepted Answer

$$70 m$,$$ $$-10 m$$

Question 6

Which of the following is the correct formula for average velocity $$v_{avg}$$?

Accepted Answer

$$v_{avg} = \frac{\Delta x}{\Delta t}$$

Question 7

A rocket sled accelerates at $$a = 50 m/s$^2$$ for $$5.0 s$$, then coasts for $$3.0 s at $$its final speed. What is the total distance traveled?

Accepted Answer

$$1250 m$ +$$ $$750 m$ = 2000 m$$

Question 8

Which statement is true about the sign of acceleration and velocity for an object slowing down along a straight line?

Accepted Answer

Acceleration and velocity have opposite signs.

Question 9

A cheetah accelerates rapidly, runs at top speed, then slows down. During the slowing down phase, how do the velocity and acceleration vectors relate?

Accepted Answer

They point in opposite directions.

Question 10

Which of the following is the correct formula for acceleration $$a$$?

Accepted Answer

$$a = \frac{\Delta v}{\Delta t}$$

Question 11

A student is at position $$x = 23 m. $$She then undergoes a displacement of $$-50 m. $$What is her final position?

Accepted Answer

$$-27 m$$

Question 12

Which of the following is NOT a feature of a coordinate system used to describe motion?

Accepted Answer

A fixed velocity vector at the origin

Question 13

A motion diagram shows a particle slowing down while moving in the positive $$x$$ direction. What is the sign of its acceleration?

Accepted Answer

Negative

Question 14

Which of the following is the correct SI unit for density?

Accepted Answer

$$\mathrm{kg/m^3$}$$

Question 15

A soccer ball rolls along the ground and gradually slows down. How do the velocity vectors change in the motion diagram?

Accepted Answer

They get shorter.

Question 16

Which of the following is a correct order of magnitude estimate for the mass of a bacterium?

Accepted Answer

$$10^{-15} kg$$

Question 17

When multiplying or dividing measured quantities, how should you determine the number of significant figures in the answer?

Accepted Answer

Match the number of significant figures in the least precisely known number.

Question 18

A polymerase moves along DNA at $$20 nm/s. If it $$must transcribe $$300 nm$$, how long does it take?

Accepted Answer

$$15 s$$

Question 19

Which of the following is a scalar quantity?

Accepted Answer

Mass

Question 20

A motion diagram shows a car's displacement vectors getting longer with each frame. What does this indicate about the car's motion?

Accepted Answer

The car is speeding up.

Describing Motion: Fundamental Concepts in Physics

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