Potential energy = mgh
Potential energy = 10 x 9.8 x 1.3
Potential energy = 127.4 J
Incomplete question. Missing part:
"it took him 10 seconds to move the couch. What was his power?"
Answer:
50 W
Explanation:
The power developed is given by:

where
W is the work done
t is the time taken
In this problem,
W = 500 J
t = 10.0 s
Substituting into the equation, we find

To form an ion and bond with hydrogen, the oxygen atom gains electrons. Electrons are negative, therefore the oxygen within the water molecule will be negative.
Answer:
N = 167 Newtons
R = 727 Newtons
Explanation:
i) For static equilibrium, moments about any convenient point must sum to zero.
A moment is the product of a force and a moment arm length. Only the force acting perpendicular to a moment arm passing through the pivot point makes a moment.
ii) I will <em>ASSUME </em>the two moment arms are 0.05m and 0.15 m
CCW moments about the fulcrum are
190 N(0.2 m) + 280 N(0.05 m) = 52 N•m
CW moments are (N)N(0.15 m + 90 N(0.3 m) = 27 + 0.15N N•m
For static equilibrium, these must be equal
27 + 0.15N = 52
0.15N = 25
N = 166.6666666...
Sum moments about N to zero
(Same as saying CW and CCW moments must balance)
190(0.2 + 0.15) + 280(0.05 + 0.15) - R(0.15) - 90(0.3 - 0.15) = 0
R = 726.6666666...
We could verify this by summing vertical forces to zero.
R - 190 - 280 - 166.666666 - 90 = 0
R = 726.6666666...