Answer:
250 kg/m3
Explanation:
The total volume of the raft is length times width times height
V = lwh = 2 * 3 * 0.5 = 3 m cubed
The volume of the raft that is submerged in water is 1/4 of total volume
3 /4 = 0.75 m cubed
Let water density = 1000 kg/m cubed and g = 10 m/s2
The buoyant force is equal to the weight of water displaced by the raft
F = 0.75 * 1000 * 10 = 7500 N
This force is balanced by the raft weight, so the weight of the raft is also 7500N
Mass of raft is 7500 / g = 7500 / 10 = 750 kg
Raft density is mass divided by volume = 750 / 3 = 250 kg/m3
Answer:
A)5524J,
B) 29.2Nm
Explanation:
This question can be treated using work- energy theorem
Work= change in Kinectic energy
W= Δ KE
Work= difference between the final Kinectic energy and intial Kinectic energy.
We know that
Kinectic energy= 1/2 mv^2 .............eqn(1)
This can be written in term of angular velocity, as
KE= 1/2 I
the best option would be d.) examples of constructive erosion.
Life cycles occur in a variety of forms, all involving the exploitation of one or more hosts. Those that must infect more than one host species to complete their life cycles are said to have complex or indirect life cycles, while those that infect a single species have direct life cycles.
If a parasite has to infect a given host in order to complete its life cycle, then it is said to be an obligate parasite of that host; sometimes, infection is facultative — the parasite can survive and complete its life cycle without infecting that particular host species. Parasites sometimes infect hosts in which they cannot complete their life cycles; these are accidental hosts.
A host in which parasites reproduce sexually is known as the definitive, final or primary host. In intermediate hosts, parasites either do not reproduce or do so asexually, but the parasite always develops to a new stage in this type of host
Answer:
a) 4.9W b) 3.82W
Explanation:
Stefan-Boltzmann law of radiation formulae:
Q/t (W) = sigma* e*A*T^4
Sigma = 5.67*10^-8 j/sm^2K^4 (Stefano Boltzmann constant)
e = emissivity
T = absolute temperature in kelvin and A = area in m^2
a) Q/t = 140/10000(m^2) * 0.87* 5.67* 10^-8* (290^4) = 4.9W
b) without hair the
Q/t = 140/ 10000(m^2) *0.68* 5.67* 10^-8* (290^4)
= 3.82W
