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jonny [76]
2 years ago
7

If a boy lifts a mass of 6kg to a height of 10m and travels horizontally with a constant velocity of 4.2m/s, calculate the work

done? Explain your answer.
Physics
1 answer:
kirza4 [7]2 years ago
4 0

Answer:

W = 641.52 J

Explanation:

The work done here will be the sum of potential energy and the kinetic energy of the boy. Here potential energy accounts for vertical motion part while the kinetic energy accounts for the horizontal motion part:

Work\ Done = Kinetic\ Energy + Potential\ Energy\\\\W = K.E +P.E\\\\W = \frac{1}{2}mv^2+mgh\\\\

where,

W = Work Done = ?

m = mass = 6 kg

v = speed = 4.2 m/s

g = acceleration dueto gravity = 9.81 m/s²

h = height = 10 m

Therefore,

W = \frac{1}{2}(6\ kg)(4.2\ m/s)^2+(6\ kg)(9.81\ m/s^2)(10\ m)

W = 52.92 J + 588.6 J

<u>W = 641.52 J</u>

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How long does a car (1000 kg) have a speed of 30 m/s from a rest if the engine power is 10kw
Lemur [1.5K]

Answer: 90.1 s

Explanation:

Use equation for power:

P=F*V

Use eqation for force:

F=ma

F---force

V---velocity

Vr=om/s

V=30m/s

m=1000kg

P=10000W

---------------------------

P=FV

F=P/V

F=10000W/30m/s

F=333.33N

Use equation for force to find accelartaion.

F=ma

a=F/m

a=333.33N/1000kg

a=0.333 m/s²

Use equation for accelaration to find out time:

a=(V-Vs)/t

t=(V-Vs)/a

t=(30m/s)/(0.333m/s²)

t=90.09 s≈90.1 s

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5 0
3 years ago
A spaceship moves radially away from Earth with acceleration 29.4 m/s 2 (about 3g). How much time does it take for sodium street
Gemiola [76]

Answer:

doppler shift's formula for source and receiver moving away from each other:

<em>λ'=λ°√(1+β/1-β)</em>

Explanation:

acceleration of spaceship=α=29.4m/s²

wavelength of sodium lamp=λ°=589nm

as the spaceship is moving away from earth so wavelength of earth should increase w.r.t increasing speed until it vanishes at λ'=700nm

using doppler shift's formula:

<em>λ'=λ°√(1+β/1-β)</em>

putting the values:

700nm=589nm√(1+β/1-β)

after simplifying:

<em>β=0.17</em>

by this we can say that speed at that time is: v=0.17c

to calculate velocity at an acceleration of a=29.4m/s²

we suppose that spaceship started from rest so,

<em>v=v₀+at</em>

where v₀=0

so<em> v=at</em>

as we want to calculate t so:-

<em>t=v/a</em>                                                v=0.17c      ,c=3x10⁸           ,a=29.4m/s²

putting values:

=0.17(3x10⁸m/s)/29.4m/s²

<em>t=1.73x10⁶</em>

7 0
3 years ago
If he feels the chances of low, normal, and high precipitation are 30 percent, 20 percent, and 50 percent respectively, What is
Brilliant_brown [7]

Question:

The operations manager for a well-drilling company must recommend whether to build a new facility, expand his existing one, or do nothing. He estimates that long-run profits (in $000) will vary with the amount of precipitation (rainfall) as follows:

Alternative             Precipitation                                

                        Low                Normal                 High

Do nothing    -100                       100                    300

Expand           350                       500                   200

Build new       750                       300                    0

If he feels the chances of low, normal, and high precipitation are 30 percent, 20 percent, and 50 percent respectively, What is EVPI (Expected value of Perfect Information)?

A. $140,000

B. $170,000

C. $285,000

D. $305,000

E. $475,000

Answer:

D. $170,000

Explanation:

The expected long run profits are  for

                        Low                Normal                 High

Do nothing    -100*0.3                100*0.2                   300*0.5 = 140

Expand           350*0.3                500*0.2                  200*0.5 = 305

Build new       750*0.3                300*0.2                  0*0.5    = 285

Therefore the expected long run profits are

$140,000

$305,000

$285,000

Based on his selected option being either to build new or to expand, the most profitable option is to expand

=$305,000

EVPI = EPPI-EMV =$170,000

7 0
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dezoksy [38]

Answer:

a. Wet, soft dough at 85 degrees Fahrenheit

Explanation:

Fermentation is an anaerobic process that transforms starches into simpler substances. The rising of dough is due to fermentation.

According to Harold McGee, 85°F (29°C) is the best temperature for fermenting bread dough. Temperatures below 85°F (29°C) take  much longer to ferment, and temperatures higher than that result into unpleasant flavors in the dough.

Wet, soft dough is usually more preferable because it produces a softer bread.

3 0
3 years ago
Which statement describes the atomic number?<br>​
Vadim26 [7]

Answer:The term atomic number, conventionally denoted by the symbol Z, indicates number of protons present in the nucleus of an atom, which is also equal to the number of electrons in an uncharged atom. The number of neutrons is represented by the neutron number (N)

Explanation:

6 0
3 years ago
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