Giancoli's Physics: Principles with Applications, 7th Edition
2
Describing Motion: Kinematics in One Dimension
Change chapter

2-1 to 2-3: Speed and Velocity
2-4: Acceleration
2-5 and 2-6: Motion at Constant Acceleration
2-7: Freely Falling Objects
2-8: Graphical Analysis

Question by Giancoli, Douglas C., Physics: Principles with Applications, 7th Ed., ©2014, Reprinted by permission of Pearson Education Inc., New York.
Problem 4
Q

# A rolling ball moves from $x_1 = 8.4 \textrm{ cm}$ to $x_2 = -4.2 \textrm{ cm}$ during the time from $t_1 = 3.0 \textrm{ s}$ to $t_2 = 6.1 \textrm{ s}$. What is its average velocity over this time interval?

A
$-4.1\textrm{ cm/s}$ Note: the video has incorrect units of $\textrm{ m/s}$, but it should be $\textrm{ cm/s}$.

In order to watch this solution you need to have a subscription.

VIDEO TRANSCRIPT

This is Giancoli Answers with Mr. Dychko. To calculate the average velocity, we take the difference in position divided by the change in time. So at time t 2, it's at position negative 4.2 centimeters and at time t 1, it's at position 8.4 centimeters and so we take the difference between their positions— negative 4.2 centimeters minus 8.4— and divide by the change in time— t 2 is 6.1 seconds and t 1 is 3.0 seconds. Divide this top difference by the bottom difference and you end up with negative 4.1 meters per second is the average velocity.

By joseotilio25 on Sun, 2/22/2015 - 5:25 PM

Why m/s if I have cm/s

By Mr. Dychko on Sun, 2/22/2015 - 10:12 PM

Hi joseotilio25, because... I made a typo! Thanks a lot for catching that. I've made a note above the video, and updated the quick answer. The units should be $\textrm{cm/s}$, as you say.

Cheers,
Mr. Dychko

#### Find us on:

Giancoli Answers, including solutions and videos, is copyright © 2009-2024 Shaun Dychko, Vancouver, BC, Canada. Giancoli Answers is not affiliated with the textbook publisher. Book covers, titles, and author names appear for reference purposes only and are the property of their respective owners. Giancoli Answers is your best source for the 7th and 6th edition Giancoli physics solutions.