Answer:
The wood's potential energy on the carpenter's shoulder is 150 J.
Explanation:
Given;
mass of the wood, m = 10 kg
height through which the wood was raised, h = 1.5 m
acceleration due to gravity, g = 10 m/s²
The wood's potential energy on the carpenter's shoulder is calculated as;
P.E = mgh
P.E = 10 x 10 x 1.5
P.E = 150 J
Therefore, the wood's potential energy on the carpenter's shoulder is 150 J.
<span>number of free electrons present.</span>
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:

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