1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Brut [27]
3 years ago
13

At least how many Calories does a mountain climber need in order to climb from sea level to the top of a 5.42 km tall peak assum

ing the muscles of the climber can convert chemical energy to mechanical energy with an efficiency of 16.0 percent. The total mass of the climber and the equipment is 78.4 kg. (Enter your answer as a number without units.)
Physics
1 answer:
Verdich [7]3 years ago
4 0

Answer:

Ec = 6220.56 kcal

Explanation:

In order to calculate the amount of Calories needed by the climber, you first have to calculate the work done by the climber against the gravitational force.

You use the following formula:

W_c=Mgh        (1)

Wc: work done by the climber

g: gravitational constant = 9.8 m/s^2

M: mass of the climber = 78.4 kg

h: height reached by the climber = 5.42km = 5420 m

You replace in the equation (1):

W_c=(78.4kg)(9.8m/s^2)(5420m)=4,164,294.4\ J     (2)

Next, you use the fact that only 16.0% of the chemical energy is convert to mechanical energy. The energy calculated in the equation (2) is equivalent to the mechanical energy of the climber. Then, you have the following relation for the Calories needed:

0.16(E_c)=4,164,294.4J

Ec: Calories

You solve for Ec and convert the result to Cal:

E_c=\frac{4,164,294.4}{016}=26,026,840J*\frac{1kcal}{4184J}\\\\E_c=6220.56\ kcal

The amount of Calories needed by the climber was 6220.56 kcal

You might be interested in
Match each action to its result. The strength of the electromagnet increases. The electromagnet turns off. The poles of the elec
IceJOKER [234]

Answer:

1) The strength of the electromagnet increases   →   Place a magnetic core inside the coil of wire

2) The electromagnet turns off    →    Turn off the battery supply

3) The poles of the electromagnet reverse     →    Change the direction in which the current flows

Explanation:

when current passes through a coil it behaves a an electromagnet.

Magnetic field strength is given by

B = μ N I  

N is no of turns and

I is the current through coil

μ is permeability of the medium or core in the coil.

1). Magnetic core increase permeability μ so it will strengthen magnetic field:

B = <u>μ</u> N I

2). When the battery turns off current becomes zeroi.e I=0

So B = μ N * 0

⇒ B = 0

so electromagnet turns off

3). Direction of magnetic field can be determine by right hand rule, i.e curl the fingers in the direction of current, thumb will point in the direction of north pole.

so changing current direction will change direction of magnetic field.

5 0
3 years ago
S Four point charges each having charge Q are located at the corners of a square having sides of length a. Find expressions for(
Ket [755]

The total electric potential at the center of the square due to the four charges is V  = √2Q/πÈa.

<h3>What do you mean by electric potential? </h3>

The amount of work needed to move a unit charge from a reference point to a specific point against an electric field. It's SI unit is volt.       

V = kq/r

Where V represents electric potential, K is coulomb constant, q  is Charge and r is distance between any  two around charge to the point charge.

Electric potential at O due to four charges is given by,

V = 4KQ/ r

where, r = √2a/2 = a/√2

V = 4k × Q√2/a

V  = √2Q/πÈa

The total electric potential at the center of the square due to the four charges is V  = √2Q/πÈa.

To learn more about electric potential refer to:

brainly.com/question/12645463

#SPJ4

3 0
2 years ago
An explorer is caught in a whiteout (in which the snowfall is so thick that the ground cannot be distinguished from the sky) whi
mel-nik [20]

Answer:

Explanation:

All the displacement will be converted into vector, considering east as x axis and north as y axis.

5.3 km north

D = 5.3 j

8.3 km at 50 degree north of east

D₁= 8.3 cos 50 i + 8.3 sin 50 j.

= 5.33 i + 6.36 j

Let D₂ be the displacement which when added to D₁ gives the required displacement D

D₁ + D₂ = D

5.33 i + 6.36 j + D₂ = 5.3 j

D₂ = 5.3 j - 5.33i - 6.36j

= - 5.33i - 1.06 j

magnitude of D₂

D₂²= 5.33² + 1.06²

D₂ = 5.43 km

Angle θ

Tanθ = 1.06 / 5.33

= 0.1988

θ =11.25 ° south of due west.

4 0
3 years ago
Which statement best explains how isotopes can have different masses and still be the same element?
ss7ja [257]

Your list of choices is a very short list, and doesn't include any
correct explanation.

The mass of an atom is roughly the number of protons AND neutrons
in its nucleus, but the element only depends on how many protons are there. 

Different atoms of the same element may have different numbers of
neutrons, so their masses are different.  But they're the same element,
because they all have the same number of protons.

3 0
3 years ago
In an experiment what are all the parts of an experiment that remain unchanged are called<br>​
stira [4]
The answer for this question is Control Variable because it doesn’t change throughout the experiment.
3 0
3 years ago
Other questions:
  • The density of blood is 1.05 kg/m3, find the mass of a bag of blood for a transfusion, if the volume is 1.5 m3.
    13·2 answers
  • What is the velocity of a wave with a wavelength of 9 meters and a period of 0.006
    10·1 answer
  • What is Cognitive Behavioural Therapy?
    7·2 answers
  • 2. How can people know that they've learned?
    5·1 answer
  • Charges of +5C and −9C are at a distance of 1m from each other. Which diagram represents the force between the two charges?
    7·2 answers
  • 1.a machine gun fires a ball with an initial velocity of 600m/s with an elevation of 30° with respect to the ground neglecting a
    9·1 answer
  • Help
    5·1 answer
  • Can Someone please help me! <br><br> What is deposition
    14·2 answers
  • edward travels 150 kilometers due west and then 200 kilometers in a direction 60 degrees north of west.what is his displacement
    14·1 answer
  • A block with a mass of 33.0 kg is pushed with a horizontal force of 150 N. The block moves at a constant speed across a level, r
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!