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In-s [12.5K]
3 years ago
5

which scenario involves the most work? a.pulling a box with a force of 127 newtons across the floor for 8 meters b.holding a mas

s with a force of 509 newtons in your arms for 150 seconds c.pushing against a brick wall with a force of 20 newtons for 42 seconds d.lifting a rock by exerting an upward force of 500 newtons for 1 meter
Physics
1 answer:
abruzzese [7]3 years ago
6 0
<span>Work can only be said to be done when an applied force results in displacement of the body in the direction of the applied force.

Work can only be said to be done in options a and d

a.pulling a box with a force of 127 newtons across the floor for 8 meters

work = 127 * 8 = 1016J

</span>
<span>d.lifting a rock by exerting an upward force of 500 newtons for 1 meter

Work = 500 N * 1 m = 500 J

Option D has more work.

D</span>
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A parallel-plate air capacitor is made from two plates 0.210 m square, spaced 0.815 cm apart. it is connected to a 120 v battery
GuDViN [60]

Answer:

at the beginning: 2.3\cdot 10^{-10} F

when the plates are pulled apart: 1.1\cdot 10^{-10} F

Explanation:

The capacitance of a parallel-plate capacitor is given by

C=k \epsilon_0 \frac{A}{d}

where

k is the relative permittivity of the medium (for air, k=1, so we can omit it)

\epsilon_0 = 8.85\cdot 10^{-12} F/m is the permittivity of free space

A is the area of the plates of the capacitor

d is the separation between the plates

In this problem, we have:

A=0.210 m^2 is the area of the plates

d=0.815 cm=8.15\cdot 10^{-3} m is the separation between the plates at the beginning

Substituting into the formula, we find

C=(1)(8.85\cdot 10^{-12}F/m)\frac{0.210 m^2}{8.15\cdot 10^{-3} m}=2.3\cdot 10^{-10} F

Later, the plates are pulled apart to d=1.63 cm=0.0163 m, so the capacitance becomes

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4 0
3 years ago
You observe that a mass suspended by a spring takes 0.25 s to make a full oscillation. What is the frequency of this oscillation
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Answer:

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time period, T = 0.25 s

Angular frequency, \omega = 25.13 rad/s

Given:

Time taken to make one oscillation, T = 0.25 s

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Frequency, f of oscillation is given as the reciprocal of time taken for one oscillation and is given by:

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The period of oscillation can be defined as the time taken by the suspended mass for completion of one oscillation.

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