Chapter 1, Problem 18SP

Three kids in a parking lot launch a rocket that rises into the air along a 380-m long arc

in 40 s. Determine its average speed.

To determine

The average speed of the rocket launched by the kids that rises into the air along $\text{380 m}$ arc in 40 s.

Answer to Problem 18SP

Solution:

$9.5\text{ m/s}$

Explanation of Solution

Given data:

The distance traveled by the rocket along the arc is $380\text{ m}$.

Timespan for which it travels is $40\text{ s}$.

Formula used:

Write the expression for average speed.

$v_{av}=\frac{l}{t}$

Here, $v_{av}$ is the average speed, $l$ is the total distance traveled, and $t$ is the time.

Explanation:

Recall the expression for average speed.

$v_{av}=\frac{l}{t}$

Substitute $380\text{ m}$ for $l$ and $40\text{ s}$ for $t$

$\begin{array}{c}{v}_{av}=\frac{380\text{ m}}{40\text{ s}}\\ =9.5\text{ m/s}\end{array}$

Conclusion:

The average speed of the rocket launched by the three kids is $9.5\text{ m/s}$.