A. The particles are packed more tightly in materials with more density which causes the vibrations to bounce of the partials more rapidly which makes them go faster
The velocity is 60 because you divide your distance by your time (240÷4=60)
The total amount of energy remains constant in an isolated system. It implies that energy can neither be created nor destroyed, but can be change from one form to another.
Answer:
t=2.10 s
u= 47.40 m/s
Explanation:
given that
h= 21.8 m
x= 101 m
g=9.8 m/s²
Lets take horizontal speed of ball = u m/s
The vertical speed of the car at initial condition is zero ( v= 0).
We know that

v= 0 m/s

now by putting the values
21.8 = 1/2 x 9.8 x t²
t=2.10 s
This is time when ball was in motion.
Now in horizontal direction
x = u .t
101 = u x 2.1
u= 47.40 m/s