Using the principle of floatation.
u = w............(a)
Upthrust of fluid is equal to the weight of the object.
Let the volume of the wood be V.
The upthrust u, is related to the volume submerged in water, and that is 1/5 of it volume, that is (1/5)V = 0.2V
Formula for upthrust, u = vdg
where v = volume of fluid displaced
d = density of fluid
g = acceleration due to gravity
weight, w = mg
where m = mass
g = acceleration due to gravity
From (a)
u = w
vdg = mg Cancel out g
vd = m
The v is equal to 0.2V, which is the submerged volume. Notice that the small letter v is volume of fluid displaced, and capital V is the volume of the solid.
d is density of fluid which is water in this case, 1000 kg/m³
0.2V * 1000 = m
200V = m
Hence the mass of the object is 200V kg.
But Density of solid = Mass of solid / Volume of solid
= 200V / V
= 200 kg/m³
Density of solid = 200 kg/m³
Work = force x distance
You can see time doesn’t matter (if we were talking about power, which is the RATE at which work is performed, that would be a different story).
W = 2 x 5 = 10 foot-pounds of work
Foot-pounds are gross units. Better to work in SI units when you can!
If the resistance of the Air is ignored, we can use the theory given by Galileo in which he warned that the thermal velocity of a body in free fall was given by

Where
g = Gravitational acceleration
t = time
As we can see the speed of objects in free fall is indifferent to the position that is launched (as long as the resistance of the air is ignored) or its mass.
Both bodies will end with the same thermal speed.
Answer:
See the explanation below.
Explanation:
If you connect the three bulbs 20 W each will have a total power of 60W.
Now we need to understand to assign the meaning of the word gap, that is, if the circuit is open at that point or if there is no bulb connected at that point.
If the circuit is open at Point 2, there will be no current in the circuit, so the battery will drain faster with the three bulbs 20W.
In the second event, where gap means that there are no bulbs connected at that point, it means that you have two bulbs connected in series of 80W each.
In this case the bulbs will consume 160W thus drain the battery faster than the three 20W bulbs connected in series.
Room that wont bother other people... instruments a stereo, and a sound system