The crane does NO work.
Work = (force) x (distance)
= (1,000 N) x (150 meters ?) = 150,000 joules
But the work is in the direction of the force, and it isn't the crane
pushing the material down. It's gravity.
Gravity is doing the work.
If the material was being lowered by a cable wrapped around the shaft
of an electric generator, then you could use the work done by gravity to
generate some electrical energy, and then sell the energy.
Or, if the "material" happened to be water, you could let gravity lower it
through a turbine or a water wheel, and use the work done by gravity to
grind wheat.
Yes, the crane may be raising a sweat, working against gravity. The
purpose is only to prevent gravity from doing the work too fast.
Answer:
Net upward force = 2373.72N
Explanation:
The concept of Pressure = Force/Area is applied as the steps are shown in the attachment
From that list of choices, choice 'B' is the only example of a plane,
but it doesn't 'describe' it at all.
Answer:
H = 27.35 m
Explanation:
From projectile motion, we know that;
h = (v_o)²/2g
Where;
v_o = 12 m/s
g = 9.8 m/s²
Thus;
h = 12²/(2 × 9.8)
h = 144/19.6
h = 7.35 m
Now, we are told that when the man is 20 m above the pillow, he lets go of
the rope.
Thus, greatest height reached by the man above the ground is;
H = 20 + h
H = = 20 + 7.35
H = 27.35 m
Answer:
F=50kg
D=5m
W=FD
therefore work done is 250Nm
