Answer:
M = 50 kg / sec * 60 sec = 3000 kg water that falls
PE = M g h initial potential energy of water
PE = 3000 kg * 9.8 m/s^2 * 20 m = 588,000 joules of energy lost
Answer:
9.8 Joules (rounded to 2 significant figures)
Explanation:
Work done (J)= Force(N) x distance changed (m)
- Force= 9.80665 x 0.5kg
- Force= 4.90332 Newtons
- Distance changed= 5-3
- distance changed= 2m/s
--> work done= 4.90332 x 2
work done= 9.8 Joules
When a swimmer pushes threw water to swim they are propelled forward because of the water resistance against the hand and feet.
The speed of the rock at 20 m is 34.3 m/s
Explanation:
We can solve this problem by using the law of conservation of energy: the mechanical energy of the rock, sum of its potential energy + its kinetic energy) must be conserved in absence of air resistance. So we can write:
where
:
is the initial potential energy
is the initial kinetic energy
is the final potential energy
is the final kinetic energy
The equation can also be rewritten as follows:
where:
m = 100 kg is the mass of the rock
is the acceleration of gravity
is the initial height
u = 0 is the initial speed (the rock starts at rest)
is the final height of the rock
v is the final speed when h = 20 m
And solving for v, we find:
Learn more about kinetic energy and potential energy here:
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Total mechanical energy = kinetic energy + potential energy
E = KE + PE
E = ½mv² + mgh
E = ½(0.1 kg)(2 m/s)² + (0.1 kg)(9.8 m/s²)(1.5 m)
E = 0.2 J + 1.47 J
E = 1.67 J
