Answer:
The electric force between them if the pieces of grain are 2 cm apart is
.
Explanation:
Given:
Charge on one grain, 
Charge on another grain, 
Separation between them, 
Electric force acting between two charges
separated by a distance
is given as:

Where,
is Coulomb's constant equal to
.
Now, plug in all the values and solve for
.

Therefore, the electric force between them if the pieces of grain are 2 cm apart is
.
Answer:
the right answer is The standard unit of measurement for acceleration is meters per second squared or m/s2.
Answer:
arithmetical multiplier for converting a quantity expressed in one set of units into an equivalent expressed in another.
Explanation:
Answer:
15.8 ft/s
Explanation:
= Velocity of car A = 9 ft/s
a = Distance car A travels = 21 ft
= Velocity of car B = 13 ft/s
b = Distance car B travels = ft
c = Distance between A and B after 4 seconds = √(a²+b²) = √(21²+28²) = √1225 ft
From Pythagoras theorem
a²+b² = c²
Now, differentiating with respect to time

∴ Rate at which distance between the cars is increasing three hours later is 15.8 ft/s
There are 6 significant figures as trailing zeros count.