Remember opposites attract and same charges repel each other.
Object A= negatively charged.
Object A and B attract so B must be positively charged.
Object B and C repel so because B is positively charged C must also be positively charged.
Object C and D attract and because C is positively charged, D must be negatively charged.
Answer:
The 1st Answer
Explanation:
Because kinetic energy is the energy which a body possesses by virtue of being in motion. So if the velocity of the object (cannonball in this case) decreases than so would the kinetic energy
Answer:
91.64 km
91.64 km high material would go on earth if it were ejected with the same speed as on Io.
Explanation:
According to Newton Law of gravitation:

Where:
G is gravitational constant=
For Moon lo g is:

According to law of conservation of energy
Initial Energy=Final Energy


For Jupiter's moon Io:
Velocity is given by:

For Earth Velocity is given by:

Now:





91.64 km high material would go on earth if it were ejected with the same speed as on Io.
Answer:32.24 s
Explanation:
Given
mass of runner (m)=51.8 kg
Constant acceleration(a)=
Final velocity (v)=5.47 m/s
Time taken taken to reach 5.47 m/s
v=u+at


Distance traveled during this time is


So remaining distance left to travel with constant velocity=153.57 m
thus time 

Total time=28.07+4.17=32.24 s