Answer:

Explanation:
Assuming the pith balls as point charges, we can calculate the repulsive force between them, using Coulomb's law:

We observe that the magnitude of the electric force is directly proportional to the product of the magnitude of both signed charges(
) and inversely proportional to the square of the distance(d) that separates them.
Replacing the given values, where k is the Coulomb constant:

Answer:
The mass of the box:
m = 60 kg
Explanation:
Given:
F = 150 N
g = 10 m/s²
_________
m - ?
Coefficient of friction wood on wood:
μ = 0.25
Friction force:
F₁ = μ*m*g
Newton's Third Law:
F = F₁
F = μ*m*g
The mass of the box:
m = F / ( μ*g) = 150 / (0.25*10) = 60 kg
45km/h * 0.5h= 22.5km
The car can travel 22.5km in 0.5 hours
Answer:
Explanation:
Given
Initial Moment of Inertia 
initial Spin 

Final Moment Moment of Inertia 
Conserving Angular momentum





Speed is the same as the initial: 25m/s.
*if* you need vectors though:
final velocity = (25*cos(35), -25*sin(35) ) m/s