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
Lady_Fox [76]
3 years ago
12

Consider a father pushing a child on a playground merry-go-round. The system has a moment of inertia of 84.4 kg · m². The father

exerts a force on the merry-go-round perpendicular to its 1.50 m radius to achieve a torque of 375 N · m.
(a) Calculate the rotational kinetic energy (in J) in the merry-go-round plus child when they have an angular velocity of 14.8 rpm. J
(b) Using energy considerations, find the number of revolutions the father will have to push to achieve this angular velocity starting from rest. revolutions
(c) Again, using energy considerations, calculate the force (in N) the father must exert to stop the merry-go-round in four revolutions. N
Physics
1 answer:
natulia [17]3 years ago
3 0

Answer:

Part a)

KE = 101.4 J

Part b)

N = 0.043 revolution

Part c)

F = 2.7 N

Explanation:

Part a)

As we know that the rotational kinetic energy of the merry go round is given as

KE = \frac{1}{2}I\omega^2

KE = \frac{1}{2}84.4(\omega^2)

here we know that

\omega = 2\pi(\frac{14.8}{60})

\omega = 1.55 rad/s

Now we have

KE = \frac{1}{2}(84.4)(1.55^2)

KE = 101.4 J

Part b)

Now we know that work done due to torque = change in kinetic energy

W = KE_f - KE_i

\tau (2N\pi) = 101.4 - 0

375(2\pi N) = 101.4

N = 0.043 revolution

Part c)

In order to stop it in four revolutions we have

\tau(2\pi N) = \Delta KE

FR(2\pi N) = 101.4

F(1.5)(2\pi \times 4) = 101.4

F = 2.7 N

You might be interested in
Write one general properties of non contact force​
Gekata [30.6K]

Answer:    Gravitational force between the two masses does not depend on the medium separating two masses.

3 0
3 years ago
Which type of reaction is this?<br> CH3COOH + H20 2 H+ + CH3C00
kumpel [21]

Answer:

dissociation of acetic acid (like vinegar) in water

Explanation:

CH3COOH is basically vinegar (aka acetic acid)

dissociation of acetic acid in water

so when you put vinegar in water it makes 2 hydrogen ions (H+) and acetate ( CH3C00 ) a chemical that used in making film

8 0
2 years ago
At noon on a clear day, sunlight reaches the earth\'s surface at Madison, Wisconsin, with an average intensity of approximately
Dmitrij [34]

Intensity of sunlight at given position is defined as power received per unit area

so here we can say

I = 2 kJ/s*m^2

area  on which photons are received is given as

A = 4.80 cm^2 = 4.80 * 10^-4 m^2

now we can find the power received due to sunlight

P = I*A

P = 2* 10^3 * 4.80 * 10^-4

P = 0.96 Watt

now we can say this power is due to photons that strikes on surface of earth

so here we can say

P = N\frac{hc}{\lambda}

given here that

\lambda = 510 nm

0.96 = N\frac{6.6 * 10^{-34}* 3 * 10^8}{510*10^{-9}}

0.96 = N * 3.88 * 10^{-19}

N = \frac{0.96}{3.88*10^{-19}}

N = 2.47 * 10^{18}

so it will strike 2.47 * 10^18 photons on given area per second

3 0
3 years ago
Light of frequency 2.5 x 1015 Hz illuminates a
Nikitich [7]

Answer:

h f = W + KE

Input energy equals work function plus KE of emitted electron

W = 6.63E-34 * 2.5E15 - 6.3 * 1.6E-19

W = 6.63 * 2.5 * 10^-19 - 10.1 * E-19 ev     (1ev = 1.6E-19 J)

W = (16.6 - 10.1)E-19 = 6.5E-19 J

h f = 6.5E-19 J        for electrons to be emitted with zero KE

f = 6.5E-19 / 6.63E-34 = .98E-15 / sec = 9.8E-14 / sec  (threshold)

3 0
3 years ago
The charge density of a uniformly charged disk 0.420 m in diameter is 2.92 ✕ 10−2 C/m2. What is the magnitude of the electric fi
iragen [17]

Answer:

E = {(Charge Density/2e0)*(1 - [z/(sqrt(z^2 - R^2))]}

R is radius = Diameter/2 = 0.210m.

At z = 0.2m,

Put z = 0.2m, and charge density = 2.92 x 10^-2C/m2, and constant value e0 in the equation,

E can be calculated at distance 0.2m away from the centre of the disk.

Put z = 0.3m and all other values in the equation,

E can be calculated at distance 0.3m away from the centre of the disk

3 0
3 years ago
Other questions:
  • Question:
    5·1 answer
  • The string of a bow and arrow is pulled tight.
    10·1 answer
  • In an experiment, a ringing bell is placed in a vacuum jar that does not have any air in it. What best describes why the bell is
    15·2 answers
  • Clouds, wind, and rain are part of the _____.
    6·1 answer
  • How are evaporation and transpiration similar?
    6·2 answers
  • A 66 kg person is parachuting and experiencing a downward acceleration of 2.1 m/s2. The mass of the parachute is 4.0 kg. (a) Wha
    14·1 answer
  • 50g of ice at 0°C is mixed with 50g of water at 80°C, what will be the final temperature of a mixture in
    11·1 answer
  • Energy and work are measured in
    14·2 answers
  • What is a bond between a positive and a negative ion charge?
    9·2 answers
  • To the speaker makes the sound louder.
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!