1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
garri49 [273]
3 years ago
9

An unruly student with a spitwad (a lump of wet paper) of mass 20 g in his pocket finds himself in the school library where ther

e is a ceiling fan overhead. He relieves his boredom by throwing the spitwad up at the ceiling fan where it collides with, and sticks to, the end of one of the blades of the stationary ceiling fan. Its horizontal velocity vector is perpendicular to the long axis of the blade. If the fan is free to rotate (no friction at all) and has moment of inertia I=1.4kgm2 , if the spitwad has horizontal velocity 4 m/s, and if the spitwad sticks to the fan blade at a distance of 0.6 m from the rotation axis of the fan, how much time will it take the fan to move through one complete revolution after the spitwad hits it (closest answer)?
a. 1min
b. 2min
c. 3min
d. 4min
e. 5min
f. 6min
Physics
1 answer:
jeka943 years ago
6 0

Answer:

T = 188.5 s, correct is  C

Explanation:

This problem must be worked on using conservation of angular momentum. We define the system as formed by the fan and the paper, as the system is isolated, the moment is conserved

         

initial instant. Before the crash

        L₀ = r m v₀ + I₀ w₀

the angular speed of the fan is zero w₀ = 0

final instant. After the crash

        L_f = I₀ w + m r v

        L₀ = L_f

        m r v₀ = I₀ w + m r v

angular and linear velocity are related

        v = r w

        w = v / r

        m r v₀ = I₀ v / r + m r v

         m r v₀ = (I₀ / r + mr) v

       v = \frac{m}{\frac{I_o}{r}  +mr} \ r v_o

let's calculate

       v = \frac{0.020}{\frac{1.4}{0.6  } + 0.020 \ 0.6  } \ 0.6 \ 4

       v = \frac{0.020}{2.345} \ 2.4

       v = 0.02 m / s

         

To calculate the time of a complete revolution we can use the kinematics relations of uniform motion

        v = x / T

         T = x / v

the distance of a circle with radius r = 0.6 m

         x = 2π r

we substitute

         T = 2π r / v

let's calculate

         T = 2π 0.6/0.02

         T = 188.5 s

reduce

         t = 188.5 s ( 1 min/60 s) = 3.13 min

correct is  C

You might be interested in
What does acceleration mean?
max2010maxim [7]
Acceleration occurs when velocities change.velocity changes either because the speed changes or the direction change.
8 0
3 years ago
three condensers are connected in series across a 150 volt supply. The voltages across them are 40,50 and 60 volts respectively,
ioda

Explanation:

Given that,

The voltages across them are 40,50 and 60 volts respectively, and the charge on each condenser is 6×10⁻⁸ C.

(a) Capacitance of capacitor 1,

C_1=\dfrac{Q}{V_1}\\\\C_1=\dfrac{6\times 10^{-8}}{40}\\\\C_1=1.5\times 10^{-9}\ F\\\\C_1=1.5\ nF

Capacitance of capacitor 2,

C_2=\dfrac{Q}{V_2}\\\\C_2=\dfrac{6\times 10^{-8}}{50}\\\\C_2=1.2\times 10^{-9}\ F\\\\C_2=1.2\ nF

Capacitance of capacitor 3,

C_3=\dfrac{Q}{V_3}\\\\C_3=\dfrac{6\times 10^{-8}}{60}\\\\C_3=1\times 10^{-9}\ F\\\\C_3=1\ nF

(b) The equivalent capacitance in series combination is :

\dfrac{1}{C}=\dfrac{1}{C_1}+\dfrac{1}{C_2}+\dfrac{1}{C_3}\\\\\dfrac{1}{C}=\dfrac{1}{1.5}+\dfrac{1}{1.2}+\dfrac{1}{1}\\\\C=0.4\ nF

Hence, this is the required solution.

5 0
3 years ago
Jenny is studying a compound that has two oxygen atoms and one nitrogen atom. Which statement describes the subscripts she will
STALIN [3.7K]

Answer:

She will use one 2 as a subscript.

Explanation:

Nitrogen is a chemical element with the symbol "N" and has an atomic number of 7. Thus, it is found in group (5) of the periodic table and as such it has 5 electrons in its outermost shell. Therefore, nitrogen has two (5) valence electrons.

On the other hand, oxygen has an atomic number of 8 and with the symbol "O."

When nitrogen and oxygen react chemically, they produce a compound known as nitrogen dioxide NO_{2}

In this scenario, Jenny is studying a compound that has two oxygen atoms and one nitrogen atom. Therefore, the statement which describes the subscripts she will use to write the chemical formula is, she will use one 2 as a subscript.

N + O_{2} ------>  NO_{2}

Where: 2 represents the subscript of oxygen.

7 0
3 years ago
If revenue is $3,000 and operating expenses are $4,000, cash flow equals _____. -$1,000 $1,000 -$7,000 $7,000
valkas [14]

Answer:

-$1,000

Explanation:

$3000 - $4000

4 0
3 years ago
How does Earth's surface and the structures on the surface change as a result of an earthquake? Help me pls and I will give Brai
EastWind [94]
<span>Earthquakes often cause dramatic changes at Earth's surface. In addition to the ground movements, other surface effects include changes in the flow of groundwater, landslides, and mudflows. Earthquakes can do significant damage to buildings, bridges, pipelines, railways, embankments, dams, and other <span>structures</span></span>
6 0
3 years ago
Other questions:
  • When compared to others, how is a greater velocity represented on a motion map?
    15·2 answers
  • Ryan wants to use the fermi process to estimate the number of basketballs that would fill a gymnasium. as part of the process, h
    12·2 answers
  • You are standing at rest at a bus stop. A bus moving at a constant speed of 5.00 m/s passes you. When the rear of the bus is 12.
    8·1 answer
  • A ball is thrown into the air with a vertical velocity of 50 m/s and a horizontal
    8·1 answer
  • A spacecraft orbits the Earth at height of 1600km. Calculate the escape velocity for the spacecraft.
    15·1 answer
  • _________statistics are measures that summarize the characteristics of a sample​
    6·1 answer
  • Please help! i will give brainliest :)
    6·1 answer
  • Please someone help me with this!!! ​
    11·1 answer
  • A stone that is thrown vertically upwards was having a velocity of 15m/s after reaches 2/3 of its maximum height. What is the ma
    6·1 answer
  • A transverse sinusoidal wave on a string has a period T= 25.0ms and travels in the negative x direction with a speed of 30.0 m/s
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!