An Alternate Solution for Example 1

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Example 1:

A car, initially at rest, begins to accelerate at 4.5 m/s². How fast, in m/s, will it be going in 5.0 seconds?

Solution:.

Step 1 - Understand the problem. (Same as before...)

Step 2 - Translate into physics: (Same as before...)

vo = 0 m/s

a = 4.5 m/s2

v = ?

= 5.0 s

Step 3: Find a kinematics equation: Here's the plan - we could use the equation to solve the problem, but we don't know . Wait! we have that we can use to find .

Step 4 & 5 - Substitute & Solve:

, but we don't know

Step 6 - Report the answer: (Same as before...)

The car will be going 23 m/s in 5.0 seconds.

Note that this is a 2-step solution, which requires a little more thinking than using the equation , but if this method appeals to you, by all means use it.

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[Chapter 2 Objectives]