A branch falls from a tree. How fast is the branch moving after 0.28 seconds? A. 2.7 m/s
B. 1.3 m/s
C. 4.4 m/s
D. 3.1 m/s

Explanation:

We want to find how fast a branch is falling after 0.28 seconds.

Essentially, we want to find its final velocity at exactly 0.28 seconds. We will use the following kinematic equation:

The branch fell from the tree, so it initially started at rest or 0 meters per second. The branch is in free fall, so its acceleration is due to gravity, or 9.8 meters per second squared. It falls for 0.28 seconds.

Substitute the values into the formula.

Multiply the numbers in parentheses.

Add.

The original measurement of time has 2 significant figures, so our answer must have the same. For the number we found, that is the tenth place. The 4 in the hundredth place tells us to leave the 7.

The branch is moving at a velocity of approximately 2.7 meters per second.