A rocket is launched straight up with a velocity of 8.73 m/s. How high does the rocket go?

Answer 1

When solving a kinematics problem, the first step is identifying variables—you will always know at least 3 of the 5 kinematic variables. They are displacement, time, initial velocity, final velocity, and acceleration. Second, identify the variable you seek. Next, identify the last variable—the one about which you know nothing and care nothing. This variable helps you decide which equation to use.

1. For this problem, we know
2. Initial velocity is 8.73 m/s
3. Final velocity (when it is at its highest point) is 0 m/s
4. Acceleration (from gravity) is -9.8 m/s²
5. The variable we seek is displacement.

The variable about which we do not care is time. Therefore, we are going to use an equation which does not contain time. You probably know it in this form: v_f²=v_i²⁺2aΔx. Using the values provided gives

0²=8.73²+(2)(-9.8)Δx or Δx=3.85 meters.

That is about 13 feet. Not a very exciting rocket.