Answer:
The initial velocity was U=22.14m/s
Explanation:
Step one :
Applying the third equation of motion
v² = u²+ 2as
Where v= Final velocity
U =initial velocity
a= acceleration due to gravity
S= distance or displacement
Step two :
V= 0
a= 9.81m/s²
S=25m
U=?
Step three :
Substituting into the equation we have
0²=U²+2*9.81*25
0=U²+490.5
U²=-490.5
U=√490.5
U=22.14m/s
Answer:

Explanation:
A body has acceleration when there is a change in the velocity vector, either in magnitude or direction. In this case we only have a change in magnitude. The average acceleration represents the speed variation that takes place in a given time interval.
a)

b)

Answer:
3, 4, 2
Explanation:
I can't see the final ones.
Answer:
Momentum is conserved.
Explanation:
-Momentum is conserved.
-By Newton's third law (For every action, there is an equal and opposite reaction.)-the change in momentum of gases in one direction must be balanced by an equal change in momentum of the spacecraft in the opposite direction.
Answer:
A: Sound waves produce an echo
Explanation:
because the cup is a hard smooth surface you can hear the voice