Answer:
0.018 J
Explanation:
The work done to bring the charge from infinity to point P is equal to the change in electric potential energy of the charge - so it is given by

where
is the magnitude of the charge
is the potential difference between point P and infinity
Substituting into the equation, we find

Answer:
The wife have to sit at 0.46 L from the middle point of the seesaw.
Explanation:
We need to make a sketch of the seesaw and the loads acting over it.
And by the studying of the Newton's law we can find the equation useful to find the distance of the mother sitting on the seesaw with respect to the center ot the pivot point.
A logical intuition will give us the idea that the mother will be on the side of her son to make the balance.
The maximum momentum with respect to the pivot point (0) will be:

Where L/2 is the half of the distance of the seesaw
Therefore the other loads ( mom + son) must be create a momentum equal to the maximum momentum.
If Earth was twice as far from the sun, the force of gravity attracting the Earth to the sun would be only one-quarter as strong. The correct answer will be C.
Answer:
a rock of 50kg should be placed =drock=0.5m from the pivot point of see saw
Explanation:
τchild=τrock
Use the equation for torque in this equation.
(F)child(d)child)=(F)rock(d)rock)
The force of each object will be equal to the force of gravity.
(m)childg(d)child)=(m)rockg(d)rock)
Gravity can be canceled from each side of the equation. for simplicity.
(m)child(d)child)=(m)rock(d)rock)
Now we can use the mass of the rock and the mass of the child. The total length of the seesaw is two meters, and the child sits at one end. The child's distance from the center of the seesaw will be one meter.
(25kg)(1m)=(50kg)drock
Solve for the distance between the rock and the center of the seesaw.
drock=25kg⋅m50kg
drock=0.5m
In ocean waves, water particles move with mechanical energy and energy moves with gravity
Not sure but hope it helps!