Part (a): Write an expression for the final velocity \(v_y\) of the ball when it impacts the surface of the moon assuming it is dropped from rest. This expression should be in terms of only, \(g\) (the gravitational acceleration on Earth), and elapsed time, \(t\).
Equation of motion
The acceleration due to gravity on the moon is \(g_m = \frac{1}{6}g\). Since the ball starts from rest, its initial velocity \(v_0\) is 0. The final velocity can be found using the equation \(v_y = v_0 + at\), where \(a\) is the acceleration and \(t\) is the time.
Substitute values
Substituting \(v_0=0\) and \(a = \frac{1}{6}g\), we get \(v_y = \frac{1}{6}gt\).
\(\boxed{v_y = \frac{1}{6}gt}\)
Part (b): Calculate the final velocity, \(v_y\), in meters per second.
Given values
\(g = 9.8 \, m/s^2\), \(t = 1.2 \, s\)
Substitute values
\(v_y = \frac{1}{6} (9.8 \, m/s^2) (1.2 \, s)\)
Calculate
\(v_y = 1.96 \, m/s\)
\(\boxed{1.96 \, m/s}\)
Part (c): Calculate the height \(d\), in meters, from which the ball was dropped.
Equation of motion
We can use the equation \(d = v_0 t + \frac{1}{2}at^2\), where \(d\) is the distance, \(v_0\) is the initial velocity, \(a\) is the acceleration, and \(t\) is the time.
Substitute values
Since \(v_0 = 0\) and \(a = g_m = \frac{1}{6}g\), we have \(d = \frac{1}{2} (\frac{1}{6}g) t^2 = \frac{1}{12}gt^2\).
Calculate
\(d = \frac{1}{12}(9.8 \, m/s^2) (1.2 \, s)^2 = 1.176 \, m\)
\(\boxed{1.176 \, m}\)
\(v_y = \frac{1}{6}gt\)
\(v_y = 1.96 \, m/s\)
\(d = 1.176 \, m\)