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viktelen [127]
3 years ago
5

g A person exploring a deep cave system becomes injured and needs to be rescued. The fastest way to get them is to pull them str

aight up out of the cave through a small opening just overhead, using a motor-driven cable. The lift is performed in three stages, each of them 10 m in height (total of 30 meters to extract the person). In the first stage, the person is accelerated to a speed of 5 m/s. They are then lifted at constant speed of 5 m/s, then in the last stage they are slowly decelerated to zero speed. If the person weighs 80 kg, how much work is done in each stage
Physics
1 answer:
disa [49]3 years ago
8 0

Answer:

1. W = 8848 J

2. W = 7848 J

3. W = 6848 J

Explanation:

The work (W) can be found using the following equation:

W = E_{k} + E_{p}

Where: E(k) is the kinetic energy and E(p) is the potential energy

Now let's find the work for every stage.

Stage 1:

W = E_{k} + E_{p} = \frac{1}{2}mv^{2} + mgh

Where: m is the mass, g is the gravity, h is the height, v is the speed  

W = \frac{1}{2}mv^{2} + mgh = \frac{1}{2}80 kg*(5 m/s)^{2} + 80 kg*9.81 m/s^{2}*10 m = 8848 J

Stage 2:

W = E_{k} + E_{p} = 0 + E_{p}

The kinetic energy is equal to zero because the acceleration is constant.

W = E_{p} = mgh = 80 kg*9.81 m/s^{2}*10 m = 7848 J

Stage 3:

W = E_{k} + E_{p} = \frac{1}{2}mv^{2} + mgh = -\frac{1}{2}80 kg*(5 m/s)^{2} + 80 kg*9.81 m/s^{2}*10 m = 6848 J      

I hope it helps you!

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An ideal blackbody is an object that __________.a. absorbs most of the energy that strikes it. b. only absorbs energy at ultravi
STALIN [3.7K]

Answer:

c. absorbs all the energy that strikes it.

Explanation:

<em>An ideal black body is an object that absorbs every light energy (irrespective of the wavelength and direction) that strikes it without reflecting any in return. </em>

<em>Such objects or bodies usually appear perfectly black and will only emit radiation when heated to a very high temperature.</em>

6 0
3 years ago
A 3.53-g sample of aluminum completely reacts with oxygen to form 6.67 g of aluminum oxide. find percent composition
katrin2010 [14]

The mass percent composition of aluminum is 52.9% in aluminum oxide.

Mass of the aluminum = 3.53 g

Mass of the aluminum oxide = 6.67 g.

The mass percent of a substance is the mass of the substance divided by the mass of the compound into 100.

Aluminum reacts with oxygen to form aluminum oxide.

The overall balanced equation for the reaction is,

Aluminum + Oxygen→Aluminum \: oxygen

4Al +3O _{2}→2Al _{2}O _{3}

The mass percent composition of aluminum in the aluminum oxide is,

Mass  \: percent = \frac{ Mass \:  of \:  the  \: substance}{ Mass  \: of \:  the \:  compound} \times 100

Mass  \: percent =  \frac{Mass  \: of \:  the  \: aluminum}{ Mass \:  of \:  the \:  aluminum \: oxide } \times 100

Mass \:  percent  =  \frac{3.53}{6.67 } \times 100

= 52.9 %

Therefore, the mass percent composition of aluminum is 52.9% in aluminum oxide.

To know more about aluminum oxide, refer to the below link:

brainly.com/question/25869623

#SPJ4

7 0
2 years ago
What is the dimensional formula of thermal conductivity?​
Inga [223]

Answer:

The dimension of thermal conductivity is M1L1T−3Θ−1, expressed in terms of the dimensions mass (M), length (L), time (T), and temperature (Θ). Other units which are closely related to the thermal conductivity are in common use in the construction and textile industries.

Explanation:looked it up for ya

6 0
3 years ago
What type of lever has the fulcrum between the resistance arm and the effort arm?
crimeas [40]
I’m not really sure but I think it’s D type 1 lever
4 0
3 years ago
NASA sends an unmanned lander to test conditions on the surface of Mars. What is the magnitude of the gravitational force acting
kozerog [31]

Answer:

The magnitude of the gravitational force acting on the lander on the surface of Mars is 512.46 N.

Explanation:

The Universal law of gravity is define as:

F = G \frac{M.m}{R^{2}}  (1)

Where F is the gravitational force, G is gravitational constant, M is the mass of Mars, m is the mass of the lander and R is the radius of Mars.

Before replacing the values in equation 1 it is necessary to express the radius of mars in terms of meters:

R = 3397 kmx\frac{1000 m}{1 km} ⇒ R = 3397000 m

Finally, equation 1 can be used:

F = (6.67x10^{-11} N.m^{2}/Kg^{2}) \frac{(6.42x10^{23} kg)(138.1 kg)}{(3397000 m)^{2}}

F = 512.46 N

Hence, the magnitude of the gravitational force acting on the lander on the surface of Mars is 512.46 N.

4 0
3 years ago
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