Consider a father pushing a child on a playground merry-go-round. The system has a moment of inertia of 84.4 kg.m^2. The father exerts a force on the merry-go-round perpendicular to its radius to achieve an angular acceleration of 4.44 rad/s^2.

Required:
a. How long (in s) does it take the father to give the merry-go-round an angular velocity of 1.53 rad/s? (Assume the merry-go-round is initially at rest.)
b. How many revolutions must he go through to generate this velocity?
c. If he exerts a slowing force of 270 N at a radius of 1.20 m, how long (in s) would it take him to stop them?

Answers

Answer 1

Answer:

Explanation:

Given that:

the initial angular velocity [tex]\omega_o = 0[/tex]

angular acceleration [tex]\alpha[/tex] = 4.44 rad/s²

Using the formula:

[tex]\omega = \omega_o+ \alpha t[/tex]

Making t the subject of the formula:

[tex]t= \dfrac{\omega- \omega_o}{ \alpha }[/tex]

where;

[tex]\omega = 1.53 \ rad/s^2[/tex]

[tex]t= \dfrac{1.53-0}{4.44 }[/tex]

t = 0.345 s

b)

Using the formula:

[tex]\omega ^2 = \omega _o^2 + 2 \alpha \theta[/tex]

here;

[tex]\theta[/tex] = angular displacement

[tex]\theta = \dfrac{\omega^2 - \omega_o^2}{2 \alpha }[/tex]

[tex]\theta = \dfrac{(1.53)^2 -0^2}{2 (4.44) }[/tex]

[tex]\theta =0.264 \ rad[/tex]

Recall that:

2π rad = 1 revolution

Then;

0.264 rad = (x) revolution

[tex]x = \dfrac{0.264 \times 1}{2 \pi}[/tex]

x = 0.042 revolutions

c)

Here; force = 270 N

radius = 1.20 m

The torque = F * r

[tex]\tau = 270 \times 1.20 \\ \\ \tau = 324 \ Nm[/tex]

However;

From the moment of inertia;

[tex]Torque( \tau) = I \alpha \\ \\ Since( I \alpha) = 324 \ Nm. \\ \\ Then; \\ \\ \alpha= \dfrac{324}{I}[/tex]

given that;

I = 84.4 kg.m²

[tex]\alpha= \dfrac{324}{84.4} \\ \\ \alpha=3.84 \ rad/s^2[/tex]

For re-tardation; [tex]\alpha=-3.84 \ rad/s^2[/tex]

Using the equation

[tex]t= \dfrac{\omega- \omega_o}{ \alpha }[/tex]

[tex]t= \dfrac{0-1.53}{ -3.84 }[/tex]

[tex]t= \dfrac{1.53}{ 3.84 }[/tex]

t = 0.398s

The required time it takes= 0.398s


Related Questions

When two charged particles are moving toward each other, their velocities decrease until they eventually come to a
stop. What happens afterward? (1 point)
O They remain in the same place without moving.
O They accelerate toward each other.
O they bond and accelerate together.
O They accelerate in opposite directions.

Answers

Answer: 3rd option!
They bond and accelerate together

When two charged particles are moving toward each other, they bond and accelerate together.

To find the correct statement among all the options, we need to know about electromagnetic force.

What is electromagnetic force?The force between any two dynamic charged particles is the electromagnetic force. It's a combination of electric force and magnetic force. What does happen, when two charged particles move towards each other?When two charged particles move towards each other, they combine with each other dur to the electromagnetic force. Then they are travelled together as a single particle along the direction of more acceleration.

Thus, we can conclude that the option (C) is correct.

Learn more about electromagnetic force here:

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A waterfall is an example of what energy conversion?

Answers

Answer:

most common energy transformations is the transformation between potential energy and kinetic energy. In waterfalls such as Niagara Falls, potential energy is transformed to kinetic energy. The water at the top of the falls has gravitational potential energy. As the water plunges, its velocity increases.

Explanation:

Hope this helps you

( I got this from transformation and conservation article)

An object is moving in a straight line at constant speed. A resultant torce begins to act upon
the object.
State the ways in which the force may change the motion of the object

Answers

Answer: The velocity magnitude or the velocity direction chages.

Explanation:

According to Newton's second law of motion, the acceleration of a system moved in same direction and is also directly proportional to the external force which acts on it while inversely proportional to the mass. The formula is: a = F/m

Based on the question, since the object obtains acceleration, then it can be infered that there will be changes in the velocity magnitude or the direction as a result of the motion.

A man rides a bike along a straight road at a constant speed for 5 minmin, then has a flat tire. He stops for 5 minmin to repair the flat, but then realizes he cannot fix it. He continues his journey by walking the rest of the way at a constant speed, which takes him another 10 min.

Required:
Use the particle model to draw a motion diagram of the man for the entire motion described here. Number the dots in order, starting with zero.

Answers

Use the particle model to drawl a motion diagram

You have a 6.00 V power supply, and
a 30.0 ohm and a 75.0 ohm resistor.
Find the current flowing out of the
battery if the resistors are connected
in parallel.

Answers

Answer: 0.28 A

Explanation:

Answer:

.28

Explanation:

Acellus

What is the definition of Heat Transfer

Answers

Answer:

Heat transfer is an engineering discipline that concerns the generation, use, conversion, and exchange of heat (thermal energy) between physical systems.

Explanation:

Answer:

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes.

Explanation:

hope that helps

Which is one way to determine whether a reaction was a chemical reaction or a nuclear reaction?

Answers

Answer:

Check how much energy was released during the reaction or check for a change in total mass

The total resistance of a series circuit is 15.0 ohms what is the second resistance of the first resistance is 10.0 ohms?
A. less than 5.0 ohms
B. 5.0 ohms
C. 15 ohms
D. 25 ohms

Answers

I think the answer is B

what is meant by measurementwhat are the three requirements for selecting a unit of a physical quantity ​

Answers

Answer:

Three requirements for selecting a unit are

1. The unit should be reproducible.

2. It should be possible to define the unit without ambiguity.

3. The value of the unit should not change with space and time.

Four passengers with combined mass 250 kg compress the springs of a car with worn out shock absorbers by 4.00cm when they enter it. Model the care and passengers as a single body on a single ideal spring. If the loaded has a period of vibration of 1.08 s, what is the period of vibration of the empty car?

Answers

Answer:

The time period of the empty car will be "1.00 s".

Explanation:

The given values in the question will be:

Mass,

m = 250 kg

Loaded car's time period will be:

T = 1.08 s

Shock absorbers compression,

x = 4 cm

or,

  = 0.04 m

Now,

Weight of passengers will be:

⇒  [tex]F=mg[/tex]

         [tex]=250\times 9.8[/tex]

         [tex]=2450 \ N[/tex]

The spring constant of shock absorbers will be:

⇒  [tex]k=\frac{F}{x}[/tex]

        [tex]=\frac{2450}{0.04}[/tex]

        [tex]=61.250 \ N/m[/tex]

As we know,

Time period, [tex]T = 2 \pi\sqrt{\frac{M}{k} }[/tex]

On substituting the values, we get

                   [tex]1.08=2\pi \sqrt{\frac{M}{61250} }[/tex]

                  [tex]\frac{M}{61250}=0.02955[/tex]

                      [tex]M=0.02955\times 61250[/tex]

                           [tex]=1809.6 \ kg[/tex] (Total mass of car as well as its passengers)

Now,

The mass of the empty car will be:

⇒  [tex]m'=M-m[/tex]

          [tex]=1809.6-250[/tex]

          [tex]=1559.6 \ kg[/tex]

hence,

The time period of empty car will be:

⇒  [tex]T'=2\pi\sqrt{\frac{m'}{k} }[/tex]

         [tex]=2\pi\sqrt{\frac{1559.6}{61250} }[/tex]

         [tex]=2\pi \sqrt{0.0254}[/tex]

         [tex]=1.003 \ s[/tex]

or,

         [tex]=1.00 \ s[/tex]

which chareged particles contribute to electricity, magnetism, and light

Answers

Answer:

Explanation:charged particles create an electric force field. Moving charged particles create a magnetic force field. Accelerating charged particles produce changing electric and magnetic force fields which propagate as EM waves.

POSSIBLE POINTS: 4
A sound wave traveling through a solid material has a frequency of 5 hertz. The wavelength of the sound wave is 2 meters. What is the speed of sound in
the material?
50 m/s
1,000 m/s
.
25 m/s
10 m/s
17
18 19 20 21 22 23 24 25 26
19 20 21 2
Ne
12631
MAY
20
0
étv

Answers

Answer:

v = fy

speed is equal to frequency × wavelength

5 × 2

[tex]10m.s^{ - 1} [/tex]

If you make multiple measurements of your height, you are likely to find that the results vary by nearly half an inch in either direction due to measurement error and actual variations in height. You are slightly shorter in the evening, after gravity has compressed and reshaped your spine over the course of a day. One measurement of a man's height is 6 feet and 1 inch. Express his height in meters, using the appropriate number of significant figures.

Answers

Answer:

H = 1.85 m

Explanation:

First, we will convert the height completely into inches. 1 feet contains 12 inches in it. Therefore:

H = (6 feet)(12 inch/1 feet) + 1 inch

H = 73 inches

Now, we will convert this height from inches to meters. 1 inch is equivalent to 0.0254 m. Therefore:

H = (73 inches)(0.0254 m/1 inch)

H = 1.85 m

What is the net force on a skydiver falling with a constant velocity of 0 m/s downward?

Answers

Since the velocity is constant then the there is 0 net force on him falling downward.

At what rate is thermal energy being generated in the 2R-resistor when ε = 12 V and R = 3.0 Ω?​

Answers

Answer:

6 W

Explanation:

From the given information:

The resistance in Parallel for 2R is:

[tex]R_p = \dfrac{2R\times 2R}{2R+2R} \\ \\ R_p= R[/tex]

The equivalent resistance:

[tex]R_{eq} = R_p + R = 2R[/tex]

[tex]R_{eq} = 2(3)[/tex]

[tex]R_{eq} = 6 \ \ ohms[/tex]

The current through the circuit in R is:

[tex]= \dfrac{12}{R+R} \\ \\ = \dfrac{12}{2\times 3} \\ \\ = 2 A[/tex]

The current through the circuit in 2R is:

[tex]I_2R = (2A) \times \dfrac{2R}{2R+2R}[/tex]

[tex]I_2R = 2A \times \dfrac{1}{2} \\ \\ I_2R = 1A[/tex]

Finally, the thermal energy:

[tex]P_{2R} = (1)^2 (2R)[/tex]

[tex]P_{2R} = (1)^2 (2\times 3)[/tex]

[tex]P_{2R} = 6W[/tex]

A Thomson's gazelle can run at very high speeds, but its acceleration is relatively modest. A reasonable model for the sprint of a gazelle assumes an acceleration of 4.2m/s2 for 6.5s , after which the gazelle CONTINUES at a steady speed.

a. What is the gazelles top speed?
b. A human would win a very short race with a gazelle. The best time for a 30 m sprint for a human runner is 3.6 s. How much time would the gazelle take for a 30 m race?

Answers

Answer:

The correct answer will be:

(a) 27.3 m/s

(b) 3.8 s

Explanation:

According to the question:

Acceleration,

[tex]a= 4.2 \ m/s^2[/tex]

Time,

[tex]t = 6.5 \ s[/tex]

(a)

The gazelles top speed will be:

⇒  [tex]V_{max} = at[/tex]

             [tex]=4.2\times 6.5[/tex]

             [tex]=27.3 \ m/s[/tex]

or,

             [tex]= 27 \ m/s[/tex]

(b)

As we know,

s = 30 m

Now,

⇒  [tex]s = \frac{1}{2} at^2[/tex]

or,

⇒  [tex]t=\sqrt{\frac{2s}{a} }[/tex]

On putting the given values, we get

       [tex]=\sqrt{\frac{2\times 30}{4.2} }[/tex]

       [tex]=\sqrt{\frac{60}{4.2} }[/tex]

       [tex]=3.78 \ s[/tex]

or,

       [tex]=3.8 \ s[/tex]

A scientist wants to create a new material using nanotechnology. In which size range will she be working? 1 nm to 100 nm 1 to 10,000 nm 100 to 1000 nm 100 to 10,000 nm

Answers

Answer:

I believe it’s A

Explanation:

Answer:

A is correct (1 nm to 100 nm)

Explanation:

I just took the exam

A loudspeaker, mounted on a tall pole, is engineered to emit 75% of its sound energy into the forward hemisphere, 25% toward the back. You measure an 85 dB sound intensity level when standing 3.5 m in front of and 2.5 m below the speaker. What is the speaker’s power output?

Answers

Answer:

"0.049 W" is the correct answer.

Explanation:

According to the given question,

[tex]r = \sqrt{(3.5)^2+(2.5)^2}[/tex]

  [tex]=\sqrt{8.5}[/tex]

[tex]SL=85[/tex]

As we know,

⇒  [tex]SL=10 \ log(\frac{I}{I_o} )[/tex]

     [tex]85=10 \ log(\frac{I}{10^{-12}} )[/tex]

      [tex]I=3.162\times 1^{-4} \ W/m^2[/tex]

Now,

⇒  [tex]P_{front} = I(2\pi r^2)[/tex]

               [tex]=(3.162\times 10^{-4})(2\pi\times 18.5)[/tex]

               [tex]=0.0368 \ W[/tex]

               [tex]=0.75 \ P[/tex]

or,

                [tex]=0.049 \ W[/tex]

The Nardo ring is a circular test track for cars. It has a circumference of 12.5 km. Cars travel around the track at a constant speed of 100 km/h. A car starts at the easternmost point of the ring and drives for 30 minutes at this speed.

Required:
a. What distance, in km, does the car travel?
b. What is the magnitude of the car's displacement, in km, from its initial position?
c. What is the speed of the car in m/s?

Answers

Answer: 50 km, 0, 27.78 m/s

Explanation:

Given

Circumference of the track is [tex]12.5\ km[/tex]

Speed of car is [tex]100\ km/h[/tex]

Car drives for [tex]30\ \text{minute}\ or\ 0.5\ hr[/tex]

(a)Distance traveled is

[tex]\Rightarrow D=100\times 0.5\\\Rightarrow D=50\ km[/tex]

(b)displacement of the car

It can be observed that 12.5 is a multiple of 50, that is, 50 km can be interpreted as 4 complete rounds of the track.

Therefore, the displacement of the car is zero.

(c)To convert kmph to m/s, multiply the entity by [tex]\frac{5}{18}[/tex]

[tex]\Rightarrow 100\times \dfrac{5}{18}\\\\\Rightarrow 27.78\ m/s[/tex]

A thin film of acetone (n=1.25) lies on the surface of a thick piece of water (n=1.30). White light shines down from air onto the thin layer of acetone. Destructive interference occurs for m=3 for a wavelength in air of 600 nm. What is the thickness of the thin film?

Answers

Answer:

Explanation:

The wave of light is being reflected two times while going from lower to higher refractive index mediums

So there will be phase reversal two times .

Condition of destructive index

2 μ t = ( 2m+1) λ / 2

Substituting the values

2 x 1.25 x t = ( 2 x 3 + 1 ) x 600nm / 2

2.5 t = 2100 nm

t = 840 nm .

A book is sitting on a table. The book is
applying a 65 N down on the table.
How much force is the table exerting on the
book?

Answers

Answer:

65 Newtons

Explanation:

A book is kept on the table. The book is applying 65 N of force down on the table. So the table will also apply 65 N force to the book.

What is Force?

According to physics, a force is an effect that has the power to change an object's motion. A force can cause a massed item to accelerate or modify its velocity. A push or a pull is a straightforward method to explain force. Considering that a force has both a magnitude and a direction, it is a vector quantity.

The pace at which an object's direction changes when it is traveling is referred to as its velocity, and is measured by a particular unit of time and from a particular point of view.

When the book is applying force on the table that is mg, and it is 65 N the table will also generate a normal reaction force which will be equal to the force applied by the book which is 65 N.

To get more information about Force :

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1. In order to change the speed of a wave, you must change something about the medium. T or F

2. Diffraction is the process in which waves spread out as they pass through an opening. T or F

3. The larger the opening a wave passes through, the more the wave will diffract. T or F

Answers

Answer:

1) False

As the frequency can be defined as the number of times wave formed per unit time or in other words the numbers of a combination of a crest and trough forms. So the frequncy of a sound wave depends upon the source producing sounds

2)False

Diffraction is the process in which a light wave bends when they pass through a specified medium such as water.

3)True

hope it helps

How does a generator use the effect you noticed in the pickup coil to generate electrical energy? What energy transformations are taking place? Why does a generator make alternating current? What change would have to be made to make direct current?

Answers

Answer:

Movement of Electrons in opposite direction of the rotation of the pickup coil leads to the direction of Electrical energy ( Alternating current ).

Explanation:

For a Generator to generate electricity, Electrons that is found in the rotating coil of the Generator will experience some sort of force that makes them to start moving in a direction that is perpendicular to the direction of the rotating/pickup coil found in the Generator.

The conversion of mechanical energy (Rotation of the pickup coil ) to electrical energy takes place in the Generator

The generator makes an alternating current because electrons move in opposite direction of the rotating coil

In other to generate a Direct current using a generator we have to replace the slip rings with commutator.

It takes 24 hours for _______?


a.Earth to circle the sun one time

b.earth to rotate on its axis one time

c. The sun to circle earth one time

d.the sun to rotate on its axis one time

Answers

Answer:

C

Explanation:

Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4 seconds with respect to other, distant, stars. Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation.

Answer: the answer is b.

ps: the other answer is wrong, the earth rotates around the sun, and the sun doesn't rotate around the earth.

Explanation:

A sound has a higher pitch than a bell. Which quantity must also be higher in this sound than in the bell?
O amplitude
O frequency
O wavelength
O speed

Answers

Answer:

frequency

Explanation:

The frequency must also be higher in this sound than in the bell because for high pitch the frequency must be high.

What is the frequency?

It is defined as the number of waves that crosses a fixed point in one second, known as frequency. The unit of frequency is per second.

We have:

A sound has a higher pitch than a bell.

As we know, the sound has a high pitch if the vibration frequency is high, and a low pitch if the vibration frequency is low.

Thus, the frequency must also be higher in this sound than in the bell because for high pitch the frequency must be high.

Learn more about the frequency here:

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What did Europeans, africans and Americans trade as a result for the Colombian exchange

A. Railroad engineering ideas

B. Computer technology

C. Film production techniques

D. Agricultural knowledge

Also under the subject I meant to put social studies not physics.

Answers

Answer: Railroad engineering ideas

3.6 Make innovative suggestions on how you could instill healthy environmental values
in communities.

Answers

You could hold rallies which attract a lot of people, they come and you discuss apon making the world a better place and how you want to shape the society.

3. A dog walks 12 meters to the east and then 16 meters back to the west.
For this motion, what is the distance moved?
What is the magnitude and direction of the displacemeni?

Answers

Answer:

[tex]distance = 16 + 12 \\ = 28 \: meters \\ \\ displacement = {}^{ + } 12 + {}^{ - } 16 \\ = - 4 \: meters \\ magnitude = > |s| = 4 \: meters[/tex]

Magnets on the tracks
How can levitating trains support the claim that magnetic fields exist between objects exerting magnetic force on each other even when there is no physical contact?

Answers

Answer:

Explanation: They levitate sort of because when to opposite forces of magnets cant go together they repel

Explain the difference between the speed of an Electromagnetic wave and its frequency?

Answers

Answer:

Electromagnetic waves differ in their wavelengths and frequencies. The higher the frequency of an electromagnetic wave, the greater its energy. The speed of an electromagnetic wave is the product of its wavelength and frequency, so a wave with a shorter wavelength has a higher frequency, and vice versa.

Explanation:

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