Answer:
Explanation:
Given
mass of children 

distance between two children 
suppose small child is at a distance of x m from pivot point
so torque of small child and heavier child must be equal



Solar it is the cheapest and widely used energy source
Answer: 50 m/s
Explanation: speed v = 2· pi·n·r = 2· 3.14· 2 s^-1· 4 m
Answer: 7.41 m/s
Explanation: By using the law of of energy, kinetic energy of the brick as it falls equals the potential energy before falling.
Kinetic energy = mv²/2, potential energy = mgh
mv²/2 = mgh
v²/2 = gh
v² = 2gh
v = √2gh
Where g = 9.8 m/s², h = 2.80m
v = √2×9.8×2.8 = 7.41 m/s