How efficient are the small and large scale solar-power systems used in individual homes and industrial settings?

A 2,100 kg car is lifted by a pulley. If the cable breaks at 4.50 m, what is the velocity of the car when it hits the ground

kirill [66]

The problem involves the conversion of potential energy to kinetic energy as the object falls from rest. Energy is conserved, so the equation used is:

PEi + KEi = PEf + KEf

Since the object is falling from rest, the initial kinetic energy is zero. Also, since the object hits the ground at its final position, the final potential energy is zero. This leaves:

PEi = KEf
mgh = 1/2 mv^2

*cancel out mass on both sides of the equation

gh = 0.5v^2
v = sqrt(2gh) = sqrt(2*9.81*4.5) = 9.40 m/s --> final ans.

4 0

3 years ago

When the daughter nucleus produced in a radioactive decay is itself unstable, it will eventually decay and form its own daughter

Dmitrij [34]

Answer:

4.981 MeV

Explanation:

The quantity of energy Q can be calculated using the formula

Q = (mass before - mass after) × c²

Atomic Mass of thorium = 232.038054 u, atomic of Radium = 228.0301069 u and mass of Helium = 4.00260. The difference of atomic number and atomic mass between the thorium and radium ( 232 - 228) and ( 90 - 88) show α particle was emitted.

1 u = 931.494 Mev/c²

Q = (mass before - mass after) × c²

Q = ( mass of thorium - ( mass of Radium + mass of Helium ) )× c²

Q = 232.038054 u - ( 228.0301069 + 4.00260) × c²

Q = 0.0053471 u × c²

replace 1 u = 931.494 MeV/ c²

Q = 0.0053471 × c² × (931.494 MeV / c²)

cancel c² from the equation

Q = 0.0053471 × 931.494 MeV = 4.981 MeV

3 0

3 years ago

Why do streets and highways have speed limits rather than velocity limits?

andrew11 [14]

They actually DO have velocity limits. There are legal restrictions on both speed and direction.

-- Speeds are limited according to the black numbers on white signs that you see on sign-posts everywhere.

-- Directions are limited by the layout of the pavement and curbs on all the highways, avenues, roads, boulevards and streets, as well as the countless signs that say "One Way", "No Left Turn", "Keep Right", "Keep Left", etc. Violate one of these, and you get nailed as sure as if you had exceeded a posted speed limit.

8 0

3 years ago

Light emitting diode (LEDs) light bulbs have become required in recent years, but do they make financial sense? Suppose a typica

kogti [31]

Answer:

The break even cost is $0.0063825

Explanation:

Break-even cost is the amount of money, or change in value, which equates to the amount at which an asset must be sold to equal the cost of acquiring it. For easier understanding it can be thought the amount of money for which a product or service must be sold to cover the costs of manufacturing or providing it.

Wattage = W

Cost per kilo watt hour = C

Number of hours per year = H

Price per bulb/CFL = P

Discount rate = 11%

Life of bulb = 2 years

Price of bulb = $0.39

Wattage consumption of bulb per hours = 60

Life of CFL = 24 years

Price of CFL = $3.10

Wattage consumption of CFL per hour = 15

Calculate the Equated Annual Cost (EAC) of bulb

EAC = {- P - (W/1000 x H x C) x (PVIFA 11%, 2years)}/ (PVIFA 11%, 2years)

PVIFA 11%, 2years = Annuity PV Factor = [1 – {(1 + r)^(-n)}]/r, where r is the rate per period and n is the number per periods

PVIFA 11%, 2 years = [1 – {(1 + 0.11)^(-2)}]/0.11 = 1.712523 (for 2 years)

PVIFA 11%, 24 years = [1 – {(1 + 0.11)^(-24)}]/0.11 = 8.348136 (for 2 years)

Calculate the EAC of bulb

EAC = {- P - (W/1000 x H x C) x (PVIFA 11%, 2 years)}/ (PVIFA 11%, 2 years)

EAC = {- 0.39 - (60/1000 x H x C) x (1.712523)}/ (1.712523)

EAC = {-0.39 – (51.37570 x C)}/ 1.712523, consider this equation 1

Calculate the EAC of CFL

EAC = {- P - (W/1000 x H x C) x (PVIFA 11%, 24 years)}/ (PVIFA 11%, 24 years)

EAC = {- 3.10 - (15/1000 x 500 x C) x (8.348136)}/ (8.348136)

EAC = {-3.10 – (62.61102 x C)}/8.348137, consider this equation 2

Equate 1 and 2 to find the amount of C

{-0.39 – (51.37570 x C)}/ 1.712523 = {-3.10 – (62.61102 x C)}/8.348137

{-0.39 – (51.37570 x C) x 8.348137} = {-3.10 – (62.61102 x C) x 1.712523}

C = $0.0063825

Thus, the break- even cost per kilo – watt is $0.0063825

3 0

2 years ago

What is true of both gravity and magnetism?

stira [4]

Explanation:

I want to say option B - Both forces can act without objects touching.

5 0

3 years ago