Answer:
1. 0.574 kJ/kg
2. 315.7 MW
Explanation:
1. The mechanical energy per unit mass of the river is given by:


Where:
Ek is the kinetic energy
Ep is the potential energy
v is the speed of the river = 3 m/s
g is the gravity = 9.81 m/s²
h is the height = 58 m

Hence, the total mechanical energy of the river is 0.574 kJ/kg.
2. The power generation potential on the river is:

Therefore, the power generation potential of the entire river is 315.7 MW.
I hope it helps you!
Answer:
10 kg
Explanation:
Assuming a frictionless surface, then force F=ma where F is the applied force, m is the mass and a is acceleration. Making m the subject of the formula then 
Substituting 100 N for the applied force F and 10 m/s^2 for acceleration a then the value of m will be 
Therefore, in terms of kilograms, the bookshelf weighs 10 Kg
A wind turbine turns wind energy into electricity using the aerodynamic force
Why does a satellite in a circular orbit travel at a constant speed? why does a satellite in a circular orbit travel at a constant speed? there is a force acting opposite to the direction of the motion of the satellite. there is no component of force acting along the direction of motion of the satellite. the net force acting on the satellite is zero. the gravitational force acting on the satellite is balanced by the centrifugal force acting on the satellite?
..b.25