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Mice21 [21]
3 years ago
7

Hannah just finished building a house of cards that stands four stories high. She is worried that it will fall down. Which of th

e following statements must be true?
If no unbalanced force acts upon the house of cards, then it will remain standing forever.
As long as nobody touches the house of cards, it will remain standing.
If Hannah adds another card to the house of cards, then it will fall down.
A house of cards is too fragile and must fall down eventually due to gravity.
Physics
2 answers:
Tju [1.3M]3 years ago
6 0
A.) <span>If no unbalanced force acts upon the house of cards, then it will remain standing forever.

[ Other Statements doesn't make any sense in Physics, they can be true in some situation & can't be false, option A is the only answer ]
Hope this helps!</span>
Morgarella [4.7K]3 years ago
6 0

Answer: If no unbalanced force acts upon the house of cards, then it will remain standing forever.

Explanation:

From Newton's first law we understand that for an object to change its state of rest or motion, an external unbalanced force must act on it.

In the given situation, the house of cards is at rest and would remain at rest until and unless an unbalanced external force acts on it. Thus, till then it would remain standing still.

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SHOW ADEQUATE WORKINGS IN THIS SECTION
cluponka [151]

Answer:

12 i. The work done by Wale = 107.910 kJ

The work done by Lekan = 117.720 kJ

Total work done = 225.36 kJ

ii. Wale's power =  4.3164 kW

Lekan's power = 3.924 kW

Wale has more power and is more powerful than Lekan

13. 313.92 N

Explanation:

i. The work done, W = Force, F × Distance moved by the force, D

The given parameters are

The mass of Wale = 55 kg

The mass of Lekan = 60 kg

The acceleration due to gravity, g =9.81 m/s²

The motion force of Wale and Lekan are;

Motion force of Wale = 9.81 × 55 = 539.55 N

Motion force of Lekan = 9.81 × 60 = 588.6 N

The work done by Wale = 539.55 × 200 = 107910 J = 107.910 kJ

The work done by Lekan= 588.6 × 200 = 117720 J = 117.720 kJ

107910 + 117720 =225630 J = 225.36 kJ

ii. Power = Work done/time

Wale finished the race in 25 s, therefore, his power = 107910/25 = 4316.4 W

Lekan finished the race in 30 s, therefore, his power = 117720/30 = 3924 W

Wale has more power and is more powerful than Lekan

13. The velocity ratio = 5

V. R. = Distance moved by effort/(Distance moved by load)

Efficiency = 80%

Work done by effort = x

Work done by machine = Efficiency × Work done by effort  = 0.8 × x

Distance moved by effort, E = V. R. × Distance moved by load, D = 5 × D

Work done by effort = Force × Distance moved = 200×9.81× E

Work done by effort = 1962×E = 1962×E = 1962×5×D

Work done by machine = 1962 × D, when D = 1, we have;

0.8 × 1962×1 = 1569.6 J

Work done by effort = Force × Distance moved

Work done by effort = Force × 5×D = Force × 5 (D = 1)

From the principle of conservation of energy, we have;

Energy is neither created nor destroyed

Therefore

Work done by effort = Force × 5 = 1569.6 J

Force = 1569.6 /5 = 313.92 N.

3 0
3 years ago
Light of wavelength 630 nm falls on two slits and produces an interference pattern in which the third-order bright red fringe is
goblinko [34]

Answer:

d \frac{x}{l} = m×  λ⇒ d = λ ×m×l / x

= 630×10^{-9} m × 3×3m/ 45×10^{-3} m

= 1.26×10^{-4}m

Explanation:

the above calculation is based on Young’s double slit experiment where the two slits provide two coherent light sources which results either constructive interference or destructive interference when passing through a double slit.

6 0
2 years ago
Imagine that a hypothetical life form is discovered on our moon and transported to Earth. On a hot day, this life form begins to
almond37 [142]

Answer:

The heat of vaporization 580 cal/g times 602g = cal in human  and do the same for life form.

Explanation:

4 0
3 years ago
If the AMA of the inclined plane below is 2, calculate the IMA and efficiency. IMA = Efficiency =
wlad13 [49]

Answer:

IMA = 2.5 metres

EFFICIENCY = 80%

Explanation:

The AMA of a machine is referred to as the Actual Mechanical Advantage of a machine, calculated as the ratio of the output to the input force.

The Ideal Mechanical Advantage is the ratio of the input distance to the output distance.

From the diagram, the input distance which is also the distance moved by effort  = 5metres

The load distance (output distance) = 2 metres

IMA = INPUT DISTANCE / OUTPUT DISTANCE

IMA = 5metres / 2 metres = 2.5 meters

Efficiency is the ratio of AMA TO IMA

AMA = 2, IMA = 2.5

EFFICIENCY = AMA / IMA

EFFICIENCY = (2 / 2.5) × 100%= 0.8 × 100%

EFFICIENCY = 80%

5 0
2 years ago
Based on their colors, which of the following stars is hottest? Which is coolest? Archenar (blue), Betelgeuse (red), Capella (ye
Cloud [144]

Answer: The hottest star is Archenar( blue) and the coolest star is Betelgeuse

Explanation:

Objects emit radiation that depends exclusively on their temperature. At an ambient temperature, the radiation emitted by an object is in the infrared spectrum (we could only see it with a special camera). If we heat it we will see that it first turns red (whose state we call “red hot”) because it is the lowest and least energetic wavelength of all.

If we continue to heat it, the wavelength that it emits to one with more energy will continue to increase and we will see that it turns yellow and then white. This is a signal that is emitting at all frequencies (but mainly in blue).

If we continue to warm a body that is "white hot", it would emit in the ultraviolet spectrum, with what would become ... black! then we would not see it emits light in the visible spectrum (well, we would see a very faint bluish light corresponding to the tail of the distribution of the spectrum it emits, but the peak of that spectrum would be in the ultraviolet).

6 0
3 years ago
Read 2 more answers
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