Physics, 02.12.2019 21:31 Yasminl52899

If a crane worker lifts a crate with a mass of 200 kg from the ground to a
shipping container that is 45 meters off the ground, by how much has the
worker increased the gravitational potential energy of the crate? (recall that g
= 9.8 m/s2)

a. 88,200 j
b. 31,900 j
c. 63,500 u
d. 48,100 j

Answers: 2

Show answers

Answers

Answer from: arnold2619

A. 88,200 J

Explanation:

Given data,

The mass of the crate, m = 200 kg

The height of the shipping container, h = 45 m

The gravitational of a body is possessed by the body due to the virtue of its position.

The formula for gravitational potential energy is,

P.E = mgh joules

Substituting the values

P.E = 200 x 9.8 x 45

= 88,200 J

Hence, the gravitational potential energy of the crate is, P.E = 88,200 J

Answer from: Quest

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

$p(t)=0.3t^2+6t+80$

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

$p(0)=0+0+80=80$

according to question, we have said that if the population has twice its initial population, then it becomes

$p(t)=2\times 80=160$

so, time taken to reach this above mentioned population is given by

$160=0.3t^2+6t+80\\\\160-80=0.3t^2+6t\\\\80=0.3t^2+6t\\\\0.3t^2+6t-80=0\\\\\text{using quadratic formula ,we get }\\\\t_{1,\: 2}=\frac{-60\pm \sqrt{60^2-4\cdot \: 3\cdot \: 800}}{2\cdot \: 3}\\\\t=-29.14\ and\ t=9.149$

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.

Answer from: Quest

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

so, refractive index of medium = 300000/200000 = 1.5

1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

Another question on Physics

Physics, 22.06.2019 00:30

Glass is transparent to visibile light under normal conditions; however, at extremely high intensities, glass will absorb most of the light incident upon it. this works through a process known as multiphoton absorption. in this process, several photons are absorbed at the same time. if very intense light whose photons carry 2ev of energy is shined onto a material with a band gap of 4ev, that light can be absorbed through two-photon absorption, because two photons have the right amount of energy to bridge the band gap. what is the minimum number of photons of 800-nm light that are needed to equal or exceed the band gap of fused silica glass

Answers: 1

Answer

Physics, 22.06.2019 01:00

Avehicle has an oil leak that is causing the entire oil pan to be wet, but inspection reveals no exact source after cleaning off the oil residue. technician a says to install a fluorescent dye in the crankcase and operate the engine, then re-inspect for leaks with a special light (black light). technician b says the oil leak may be coming from a source at the top of the engine, such as a valve cover gasket. who is correct?

Answers: 1

Answer

Physics, 22.06.2019 03:00

If it takes a planet 2.8 x 10^8 s to orbit a star with a mass of 6.2 x 10^30 kg what is the average distance between the planet and the star

Answers: 3

Answer

Physics, 22.06.2019 18:30

An object in mechanical equilibrium is an object

Answers: 2

Answer

You know the right answer?

If a crane worker lifts a crate with a mass of 200 kg from the ground to a
shipping container...