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2 years ago

When a deck of cards slips out of your hands and falls to the ground, gravity does work on it

Physics

2 answers:

gulaghasi [49]2 years ago

8 0

Answer:

Yes

Explanation:

But it falls slowly because it has air resistant acting on it. But when solving questions we usually ignore air resistance and take it as 0.

motikmotik2 years ago

3 0

Answer:

yes

Explanation:

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What is the difference between the law of conservation of energy and conserving energy

babymother [125]

law of conservation of energy is states that energy of the universe remains constant cant be created nor destroyed and conserving energy is not using as much power as you was like trying to make power bill lower while law of conservation is constant

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2 years ago

An egg rolls off a kitchen counter and breaks as it hits the floor. The counter is 1.0 m high, the mass of the egg is about 50 g

crimeas [40]

Use equations of motion to find the velocity just before it hits the floor:
Vf^2 = Vi^2 + 2gx 
Final velocity = 4.42m/s 

Impulse is change in momentum so: 
m(Vf - Vi) = 0.05(0 - 4.42) 
= - 0.221 kg.m/s

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2 years ago

Your friend tells you “I no the moon does not rotate because we always see the same side.” do you agree or disagree with your fr

nydimaria [60]

Answer:

no the moon does not rotate it only goes in circle just like the sun so I disagree with your friend

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2 years ago

Enter the expression 2cos2(θ)−1, where θ is the lowercase Greek letter theta.

vlabodo [156]

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4 0

2 years ago

Energy is conventionally measured in Calories as well as in joules. One Calorie in nutrition is one kilocalorie, defined as 1 kc

Sergeeva-Olga [200]

Answer:

a) The student must run flight of stairs to lose 1.00 kg of fat 709.5 times.

b) Average power

P(w)= 1062.07 [w]

P(hp)=1.42 [hp]

c) This activity is highly unpractical, because the high amount of repetitions he has to due in order to lose, just 1 Kg of fat.

Explanation:

First, lets consider the required amount of work to move the mass of the student. (considering running stairs just as a vertical movement)

Work:

$W= F*d= m*g*d$

Where m is the mass of the student, g is gravity (9.8 m/s) and d is the total distance going up the stairs (0.15m *85steps= 12.75m )

$W= F*d= m*g*d=85* 9.8*12.75=10620.75 [J]$

Converting from Joules to Kcals:

$\frac{10620.75}{4186} =2.537 Kcal$

Now lets take into account the efficiency of the human body (20%)

2.537 ---> 20%

x ---> 100%

$x=\frac{2.537*100}{20} =12.685$

So the student is consuming 12.685 KCals each time he runs up the stairs.

Now,

1 g --> 9 Kcals

1000 g --> 9000KCals

Burning 1 g of fat, requieres 9 KCals, 1000g burns 9000KCals. So in order to burn a 1Kg of fat:

$\frac{9000Kcals}{12.685Kcals} =709.5 times$

He must run up the stairs 709.5 times, to burn 1 Kg of fat.

********************

For b) just converting units, taking into account the time lapse. (53103.75 is the 100% of the energy in joules, from converting 12.685Kcals to joules)

$Power=\frac{Joules}{Seconds} =\frac{53103.75}{50} =1062.075 [W]\\$

$P(hp)=\frac{P(w)}{745.7} =\frac{1062.075}{745.7} =1.42[hp]$

*****

4 0

3 years ago