General physicsLesson 1 of 1 in the course Kinematics

Average and Instantaneous Acceleration: Direction, Signs, and Deceleration

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Acceleration describes how velocity changes over time. It matters because motion can change not only when an object speeds up or slows down, but also when it changes direction.

Average acceleration is the change in velocity divided by the time interval in which that change occurs. If an object's initial velocity is v0v_0 at time t0t_0 and its final velocity is vfv_f at time tft_f, then

All flashcards

What is average acceleration?
The change in velocity divided by the elapsed time: aˉ=Δv/Δt\bar{a}=\Delta v/\Delta t.
What does the bar over aa indicate?
It indicates acceleration averaged over a time interval, rather than at one instant.
What is instantaneous acceleration?
The acceleration of an object at a particular instant.
Why can an object accelerate at constant speed?
A change in direction changes velocity even if speed remains constant.
What does a negative acceleration value indicate?
Acceleration points in the negative direction of the chosen coordinate system.

Quiz questions

  1. What does instantaneous acceleration describe?Answer: Acceleration at a particular moment.
  2. A car travels around a bend at constant speed. Why is it accelerating?Answer: Its direction changes, so its velocity changes.
  3. When velocity and acceleration point in the same direction, what happens to speed?Answer: It increases.
  4. What does a nearly horizontal acceleration-versus-time graph indicate?Answer: Acceleration is approximately constant.
  5. If right is positive, what does negative acceleration indicate?Answer: Acceleration points to the left.

Based on College Physics 2e by Paul Peter Urone, Roger Hinrichs (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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