The center of mass is given with this formula:

Velocity is:

So, for the velocity of the center of mass we have:

In our case it is:
In order to tell a river lock attendant that you wish to go through the lock, you should <span>sound one prolonged blast followed by one short blast.
You should wait about 400 feet away from the lock and wait for the flashing light signal that allows you to enter.
Also note that </span><span>commercial traffic always have the first priority in entering the locks.</span>
The density of the material would be
25/6 grams per cm^3.
to obtain the result above this is what we do:
density is calculated as: (the mass of the given material or object) / volume of the material
which leads us to 50grams /12cm^3
consider the motion along the horizontal direction :
v₀ = initial velocity in horizontal direction as the ball rolls off the table = 3.0 m/s
X = horizontal displacement of the ball = 2.0 m
a = acceleration along the horizontal direction = 0 m/s²
t = time taken to land = ?
using the kinematics equation
X = v₀ t + (0.5) a t²
2.0 = 3.0 t + (0.5) (0) t²
t = 2/3
consider the motion of the ball along the vertical direction
v₀ = initial velocity in vertical direction as the ball rolls off the table = 0 m/s
Y = vertical displacement of the ball = height of the table = h
a = acceleration along the vertical direction = 9.8 m/s²
t = time taken to land = 2/3
using the kinematics equation
Y = v₀ t + (0.5) a t²
h = 0 t + (0.5) (9.8) (2/3)²
h = 2.2 m
C 2.2 m