I think the correct answer from the choices listed above is the last option. When electrical energy is converted into thermal energy, the <span>total amount of thermal energy plus electrical energy doesn't change. This is base on the Law of Conservation of energy where energy cannot be created or destroyed. </span>
m = mass of the box
N = normal force on the box
f = kinetic frictional force on the box
a = acceleration of the box
μ = coefficient of kinetic friction
perpendicular to incline , force equation is given as
N = mg Cos30 eq-1
kinetic frictional force is given as
f = μ N
using eq-1
f = μ mg Cos30
parallel to incline , force equation is given as
mg Sin30 - f = ma
mg Sin30 - μ mg Cos30 = ma
"m" cancel out
a = g Sin30 - μ g Cos30
inserting the values
1.20 = (9.8) Sin30 - (9.8) Cos30 μ
μ = 0.44
Answer:
(a) -1.18 m/s
(b) 0.84 m/s
Explanation:
(a)
The total linear momentum before the lumberjack begins to move is zero because all parts of the system are at res
From the law of conservation of momentum
m1v1+m2v2=0 hence m1v1=-m2v2 where m1 is mass of lumberjack, v1 is velocity of lumberjeck, m2 is mass of floating log, v2 is velocity of the floating log.
Substituting M1 for 103 Kg, V1 for 2.93 m/s, M2 for 255 Kg into the above equation we obtain
103Kg*2.93 m/s=-255Kg*V2
V2=-(103 kg*2.93 m/s)/255=-1.183490196 m/s
Hence V2=-1.18 m/s
(b)
For the second log
V(M1+M2)=m1v1 where V is the common velocity
V(103 Kg+255 Kg)=103 Kg*2.93 m/s
V=(103 Kg*2.93 m/s)/(103 Kg+255 Kg)=0.842988827 m/s
V=0.84 m/s
28.9 m/s is your answer...
Answer: b- covection
Explanation:
Conduction: It is the circulation or transfer of heat through a metal or solid. For example, heat generated inside an enclosure can be transferred to the outer surface by means of conduction.so therefore conduction can not be the answer.
Convection is the circulation or tansfer of heat from a surface by means of a fluid such as air. Natural convection happens when air is heated: it expands, rises, and is replaced by cooler air. The amount of convection may be increased by using a fan to increase the flow of air.Likewise,Ducts are used to circulate air in the system. Since, air is circulated in the system, heat is transfered by convection.Hence,the answer is B-convection.
Radiation: Here, energy is radiated through the air by means of electromagnetic radiation. Since heat transfer through raidation does not involve contact between the heated object and the heated source,so energy is lost as light or through electromagnetic radiation. So C is wrong.