The law of conservation of mass states that
1 answer:
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Answer:
The answers to the questions are;
a. The number of times the student run the flight of stairs to lose 1.00 kg of fat is 829.23 times.
b. The average power output, in watts and horsepower, as he runs up the stairs is 158.026 watts.
c. The act of climbing the stairs is not a practical way to lose weight has to lose 1 kg of fat, the student needs to workout for about 26.49 hrs or 1.104 days.
Explanation:
To solve the question, we write out the known variables as follows
1 g of fat = 9.00kcal
Number of steps the student climbs = 95 steps
Height of each step = 0.150 m
Time it takes for the student to reach the top of the stairs = 57.5 s.
Efficiency of human muscles = 20 %
Mass of student, m = 65 kg
a. From the question, the energy expended by the student in climbing the stairs is the "work done" by the student.
The "work done" is the height climbed resulting in the gaining of gravitational potential energy P. E..
That is work done, W, = P. E. = m·g·h
Where:
h = The total height climbed by the student
g = Acceleration due to gravity = 9.81 m/s²
Therefore;
h = Height of each step × Number of steps the student climbs =
= 0.150 m/(step) × 95 steps = 14.25 m
Therefore, P. E. = 65 kg × 9.81 m/s² × 14.25 m = 9086.5125 kg·m²/s²
= 9086.5125 J
We remember that the efficiency of the muscle is 20 %
The formula for efficiency is
Efficiency =
The work produced by the muscle = Energy Output = 9086.5125 J
Energy input is given by
= 9086.5125 J/ (0.2) = 45432.5625 J
= 45.432 kJ
From the question, 1 g of fat = 9.00 kcal and
1 kcal = 4186 J
Therefore 1 g of fat can release 9.00 kcal × 4186 J = 37674 J
Therefore 1 kg of fat = 1000 g = 1000 × 37674 J = 37674 kJ
To consume the energy in 1 kg of fat the student therefore will run up the foight of stairs times to make up the 37674 kJ energy contained in 1 kg of fat
That is = 829.23 times
b. Power is the rate of doing work
That is Power output = =
= 158.026 watts
c. No as the activity student will have to spend a total time of
829.23 × 57.5 s = 47680.67 s climbing up the stairs alone and
47680.67 s = 13.24 Hours climbing up of which if the time to climb down is the same s climbing up, then we ave total time = 2× 13.24 Hours
= 26.49 hrs = 1.104 days exercising which is not humanly possible.
Answer:
The wavelength of radio waves is much longer than the wavelength of visible light waves
Explanation:
Electromagnetic waves are periodic oscillations of the electric and the magnetic fields, occuring in a plane perpendicular to the direction of motion the wave.
Electromagnetic waves are the only waves able to travel in a vacuum; they travel at the speed of light:
Electromagnetic waves are also classified into 7 different types, according to their wavelength/frequency. From longest to shortest wavelength, we have: (with the corresponding wavelength written in the brackets):
Radio waves (>1 m)
Microwaves (1 mm - 1 m)
Infrared (750 nm - 1 mm)
Visible light (380 nm - 750 nm)
Ultraviolet (10 nm - 380 nm)
X-rays (0.01 nm - 10 nm)
Gamma rays (<0.01 nm)
So from the table, we can see that:
The wavelength of radio waves is much longer than the wavelength of visible light waves.
Explanation:
Given that,
Mass of the block, m = 12.2 kg
Initial velocity of the block, u = 6.65 m/s
The coefficient of kinetic friction,
(a)The force of kinetic friction is given by :
mg is the normal force
So,
(b) Net force acting on the block in the horizontal direction,
f = ma
a is the acceleration of the block
(c) Let d is the distance covered by the block before coming to the rest. Using third equation of motion as follows :
Hence, this is the required solution.