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2 years ago

A disk of radius 25 cm spinning at a rate of 30 rpm slows to a stop over 3 seconds. what is the angular acceleration?

Physics

1 answer:

SCORPION-xisa [38]2 years ago

5 0

Answer:

α = -π/3 rad/s²

θ = 1.5π rad ≈ 4.71 rad

θ = 0.75 rev

Explanation:

30 rev/min (2π rad/rev) / (60 s/min) = π rad/s

α = (ωf - ωi) / t = (0 - π) / 3 = -π/3 rad/s²

θ = ½αt² = ½(π/3)3² = 1.5π rad ≈ 4.71 rad

θ = 1.5π rad / 2π rad/rev = 0.75 rev

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A person observes a firework display for A safe distance of .750 km. Assuming that sound travels at 340 m/s in air what is the t

WINSTONCH [101]

Answer:

t = 2.2 s

Explanation:

Given that,

A person observes a firework display for A safe distance of 0.750 km.

d = 750 m

The speed of sound in air, v = 340 m/s

We need to find the between the person see and hear a firework explosion. let it is t. So, using the formula of speed.

$v=\dfrac{d}{t}\\\\t=\dfrac{d}{v}\\\\t=\dfrac{750\ m}{340\ m/s}\\\\t=2.2\ s$

So, the required time is 2.2 seconds.

3 0

2 years ago

A parallel-plate capacitor with plates of area 360 cm2 is charged to a potential difference V and is then disconnected from the

Softa [21]

Answer:

$Q=3.9825\times 10^{-9} C$

Explanation:

We are given that a parallel- plate capacitor is charged to a potential difference V and then disconnected from the voltage source.

1 m =100 cm

Surface area =S= $\frac{360}{10000}=0.036 m^2$

$\Delta d=0.8 cm=0.008 m$

$\Delta V=100 V$

We have to find the charge Q on the positive plates of the capacitor.

V=Initial voltage between plates

d=Initial distance between plates

Initial Capacitance of capacitor

$C=\frac{\epsilon_0 S}{d}$

Capacitance of capacitor after moving plates

$C_1=\frac{\epsilon_0 S}{(d+\Delta d)}$

$V=\frac{Q}{C}$

Potential difference between plates after moving

$V=\frac{Q}{C_1}$

$V+\Delta V=\frac{Q}{C_1}$

$\frac{Qd}{\epsilon_0S}+100=\frac{Q(d+\Delta d)}{\epsilon_0S}$

$\frac{Q(d+\Delta d)}{\epsilon_0 S}-\frac{Qd}{\epsilon_0S}=100$

$\frac{Q\Delta d}{\epsilon_0 S}=100$

$\epsilon_0=8.85\times 10^{-12}$

$Q=\frac{100\times 8.85\times 10^{-12}\times 0.036}{0.008}$

$Q=3.9825\times 10^{-9} C$

Hence, the charge on positive plate of capacitor= $Q=3.9825\times 10^{-9} C$

6 0

3 years ago

2. What process does water redeposit into a lake in the form of rain?

weqwewe [10]

The process that water redeposit into a lake in the form of rain is precipitation.

<h3>What is water runoffs?</h3>

Water runoff occurs when there is more water than land can absorb.

The water flows across the surface of the land and into nearby creeks, streams, or lakes.

Runoff can come from both natural processes and human activity.

When rain falls to the earth from clouds and runs downhill into rivers and lakes.

During evaporation, the water turns from liquid into gas, and moves from oceans and lakes into the atmosphere where it forms clouds.

<h3>What is precipitation?</h3>

Precipitation is any liquid (rain) or frozen water that forms in the atmosphere and falls back to the Earth, for example it could fall on land or into lakes and rivers.

Thus, the process that water redeposit into a lake in the form of rain is precipitation.

Learn more about precipitation here: brainly.com/question/1783904

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5 0

1 year ago

Can someone help me this question

vladimir2022 [97]

Answer:

Volume of wood is 68-50 = 18 cm³

Explanation:

<h2>Hope it helps you</h2>

4 0

2 years ago

Why would adding oil to the moving parts of a machine increase its efficiency?

luda_lava [24]

Adding oil reduces friction between the moving parts
Less energy is used

5 0

2 years ago