Skip to Content Go to sign in Skip to Primary Navigation Skip to Secondary Navigation Skip to Page Navigation Skip to Header Navigation Skip to Footer Navigation Read more about accessability options and our navigation

Physics Classroom is making strides to make our site accessible to everyone. Our site contains 6 navigation areas. The Primary, Secondary, and Page Level navigations have a screen reader version of their nav structure that allows using the left and right keys to navigate sibling navigation items, and up or down keys to navigate parent or child navigation items. The others can be navigated using tabs. The Primary Navigation handles the first 2 levels of site pages. The Secondary (which is not always available) handles the 3rd and 4th level of structure. The Page level navigation allows you to navigate the current page's headings quickly. The Header Navigation contains the Light/Dark Mode toggle, Search, Notifications and account login. The Breadcrumb Navigation contains the breadcrumb of the current page. If the current page has a breadcrumb, you can get to it by skipping to the content and tabbing in reverse (shift plus tab). The Footer Navigation contains links such as Privacy, Contact, about and terms. Some resources contain an Audio Player that can be activated by holding down the T key for 3 seconds, and then using K to pause and resume. While not every area of Physics Classroom is usable purely from keyboard and screen reader, we are committed to continue work on making this possible. If you have questions or need additional help, please use this link to contact us.

Return to screen reader navigation
Home Minds On 1D Kinematics Mission KC7 Average Acceleration Calculations Help Help 5

Mission KC7 Average Acceleration Calculations

The Question

A rightward-moving car accelerates from 55 mi/hr to 25 mi/hr in 4.2 seconds. Determine the average acceleration of the car in mi/hr/s.
 
(Note: Numbers are randomly generated and may differ from those shown here.)

Formula Fix

Acceleration (a) is the rate of change in an object's velocity. It is determined from knowledge of a velocity change (Δv) and the change in time (Δt) over which the velocity changes.
 
a = Δvelocity / Δtime = Δv / Δt

Don't be Fooled

The numerator in the acceleration equation (see Formula Fix section) is the change in velocity. A changein any value is found by subtracting the initial value from the final value. In this question, such a change will be negative. But don't be fooled! The question asks you to enter the magnitude of the acceleration; ignore + and - signs which are indicators of a direction.

A Very Fine Detail

The Minds On Physics program calculates answers accurate to several decimal places. Your answer does not need to be that precise. The program will allow you to have a 1% deviation from the right answer without being wrong. This means you should enter your answer to at least the second decimal place.

Hot Link