Answer:
Force between two identical conducting ball will be
Explanation:
We have given there is two identical conducting small spheres having charge
and 
Distance between centers of the ball is 0.290 m
So r = 0.290 m
We have to fond the electric force between the balls
According to Coulomb's law force between two charges is given by

So force 
So force between two identical conducting ball will be 
Answer:
The kinetic energy decreases, and gravitational potential energy increases.
Explanation:
The rollercoaster will slow down as it goes up the hill, so kinetic energy should not increase.
Answer:
speed of molecule ∝ 1/mass of molecule.
Explanation:
The velocities of the molecules depend on their masses. That's because if the molecules are large in size, their velocity is slower. Therefore their velocity is quicker when their size is small, since the molecules can move faster.
Therefore , it can be written as
speed of molecule ∝ 1/mass of molecule.
Given that:
Energy of bulb (Work ) = 30 J,
Time (t) = 3 sec
The power consumption = ?
We know that, Power can be defined as rate of doing work
Power (P) = Work(Energy supplied) ÷ time
= 30 ÷ 3
= 10 Watts
<em> The power consumption is 10 W.</em>