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DiKsa [7]
3 years ago
12

mary takes 6.0 seconds to run up a flight of stairs thaf is 102 meters long. if mary wieght is 87 newtons, what power has mary e

xerted
Physics
1 answer:
blondinia [14]3 years ago
7 0
It really doesn't matter how long the flight of stairs is. What we really need to know is how much height Mary gained, straight up. We don't know that. If we knew the height then the total amount of work she did would be 87 x the height in meters. The unit is joules. Then the power she delivered would be that number divided by the six seconds and that unit is watts. By the way ... it's troubling that Mary's weight is only about 20 pounds. It's doubtful that such a tiny creature could run up a flight of stairs.
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Answer:

(a) Elongation of rod = 0.19732 mm

(b) Change in diameter = 0.00651 mm

Explanation:

Circular area at end of steel rod = pi * diameter^2 / 4

Area = pi * (22 * 10^-^3)/4

Area = 3.801 * 10^(-4)    meter squared

Stress = force / area

Stress = 75000 / (3.801 * 10^-4)

Stress = 197316495 Pa     OR       0.197 GPa

Modulus of elasticity = stress / strain

200 = 0.19732 / Strain

Strain = 0.0009866     (longitudinal)

(a) Strain = change in length / initial length

0.0009866 = Elongation of rod / 200

Elongation of rod = 0.19732 mm

(b) Poisson ratio = lateral strain / longitudinal strain

0.3 = lateral strain / 0.0009866

Lateral strain = 0.000296

Lateral strain = Change in diameter / original diameter

0.000296 = Change in diameter / 22

Change in diameter = 0.00651 mm

4 0
3 years ago
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Two protons in an atomic nucleus are typically separated by a distance of 2 ✕ 10-15 m. The electric repulsion force between the
castortr0y [4]

Answer:

The magnitude of the electric force between the to protons will be 57.536 N.

Explanation:

We can use Coulomb's law to find out the force, in scalar form, will be:

F \ = \ \frac{1}{4 \pi \epsilon_0 } \frac{q_1 q_2}{d^2}.

Now, making the substitutions

d \ = \ 2.00 * 10 ^{-15} \ m,

q_1 = q_2 = 1.60 * 10 ^ {-19} \ C,

\frac{1}{4\pi\epsilon_0}=8.99 * 10^9 \frac{Nm^2}{C^2},

we can find:

F \ = \ 8.99 * 10^9 \frac{Nm^2}{C^2} \frac{(1.60 * 10 ^ {-19} \ C)^2}{(2.00 * 10 ^{-15} \ m)^2}.

F \ = 57.536 N.

Not so big for everyday life, but enormous for subatomic particles.

4 0
3 years ago
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Define s.i unit of force explanation
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◈ As per newton's second law of motion, Force is defined as the product of mass and acceleration.

Mathematically,

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Unit of mass : kg

Unit of acceleration : m/s²

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Unit of force ➠ <u>kg m/s²</u>

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3 years ago
A 30 kg child went down a 10 m tall slide. Assuming no energy was lost as friction, what was the child's velocity when he reache
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3 years ago
When a man returns to his well-sealed house on a summer day, he finds that the house is at 35°C. He turns on the air conditioner
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Answer:

1353.38 Watt

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T₂ = Final temperature of the house = 20°C

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m = mass of air in the house = 800 kg

Cv = Specific heat at constant volume = 0.72 kJ/kgK

Cp = Specific heat at constant pressure = 1.0 kJ/kgK

Heat removed

q = mCvΔT

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COP=\frac{Q}{W}\\\Rightarrow W=\frac{Q}{COP}\\\Rightarrow W=\frac{3789.47}{2.8}\\\Rightarrow W=1353.38\ W

∴ Power drawn by the air conditioner is 1353.38 Watt

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