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
andrew11 [14]
3 years ago
12

A merry-go-round on a playground consists of a horizontal solid disk with a weight of 805 N and a radius of 1.47 m. A child appl

ies a force 49.0 N tangentially to the edge of the disk to start it from rest. What is the kinetic energy of the merry-go-round disk (in J) after 2.95 s?
Physics
1 answer:
snow_tiger [21]3 years ago
8 0

Answer:

255.34 J

Explanation:

Given,

Weight of disk = 805 N

radius = 1.47 m

Force applied by the child = 49 N

time = 2.95 s

KE = ?

mass of the disk

M = \dfrac{W}{g}= \dfrac{805}{9.81} = 82.059\ Kg

Moment of inertia of the disk

I = \dfrac{1}{2}Mr^2

I = \dfrac{1}{2}\times 82.059\times 1.47^2 =88.66\ kgm^2

Torque on the child

\tau = F \times r = 49 \times 1.47 = 72.03 Nm

Angular acceleration

\alpha = \dfrac{\tau}{I}=\dfrac{72.03}{88.66} = 0.812\ rad/s^2

So, angular speed at t = 2.95 s

\omega = \alpha t = 0.812 \times 2.95 = 2.4\ rad/s

Now, KE of the merry go round

KE = \dfrac{1}{2} I \omega^2 = \dfrac{1}{2}\times 88.66\times 2.4^2 = 255.34 J

Hence, the Kinetic energy of the merry go round = 255.34 J

You might be interested in
If a ball with an original velocity of zero is dropped from a tall structure and it takes 7 seconds to hit the ground, what velo
Colt1911 [192]
The velocity of the ball when it reaches the ground is equal to B. 68.6 m/s. This value was obtained from the formula Vf = Vi + at. Vf is the final velocity. Vi is the initial velocity. The acceleration is "a", while the time of travel is "t". The solution is:

<span>Vf = Vi + at
</span>Vf = 0 + (-9.8 m/s^2) (7 s)
Vf = -68.6 m/s

The negative sign denotes the direction of the ball.
5 0
3 years ago
Read 2 more answers
Satellites remain in orbit around earth because
svetoff [14.1K]
Earth's gravity and the satellite's velocity keeps it so that it stays in orbit. (there is a more complicated side, too...) 
3 0
3 years ago
Un objeto se mueve con una rapidez constante de 8 m/s. Esto significa que el objeto: a) Aumenta su rapidez en 8m/s cada segundo
Hatshy [7]

Explanation:

Constant speed means that the object is covering equal distance in equal interval of time. The motion is called uniform motion for such case. In this problem, it is given that an object is moving with a constant speed of 8 m/s. It means that it does not change its speed. It is moving with a single speed constantly.

We can say that it moves 8 meters every second or 800 cm every second.

4 0
3 years ago
how much water is needed to produce 1kwh of electricity at a power plant that is 30% efficient if the temperature increase 10 C
Dimas [21]

The amount of water needed is 287 kg

Explanation:

The amount of energy that we need to produce with the power plant is

E=1 kWh = (1000W)(1h)=(1000W)(3600s)=3.6\cdot 10^6 J

We also know that the power plant is only 30% efficient, so the energy produced in input must be:

E_{in}=\frac{E}{0.30}=\frac{3.6\cdot 10^6}{0.3}=1.2\cdot 10^7 J

The amount of water that is needed to produce this energy can be found using the equation

E_{in}=mC\Delta T

where:

m is the amount of water

C=4186 J/kg^{\circ}C is the specific heat capacity of water

\Delta T=10^{\circ}C is the increase in temperature

And solving for m, we find:

m=\frac{E_{in}}{C\Delta T}=\frac{1.2\cdot 10^7}{(4186)(10)}=287 kg

Learn more about specific heat capacity:

brainly.com/question/3032746

brainly.com/question/4759369

#LearnwithBrainly

3 0
3 years ago
Estimate the smallest possible period of a satellite in a circular orbit around earth. (mass and radius of earth is 5.98 x 1024
myrzilka [38]
Given: Mass of earth Me = 5.98 x 10²⁴ Kg

           Radius of earth r = 6.37 x 10⁶ m

            G = 6.67 x 10⁻¹¹ N.m²/Kg²

Required: Smallest possible period T = ?

Formula: F = ma;  F = GMeMsat/r²     Centripetal acceleration ac = V²/r

               but V = 2πr/T

equate T from all equation.

F = ma

GMeMsat/r² = Msat4π²/rT²    

GMe = 4π²r³/T²

T² = 4π²r³/GMe  

T² = 39.48(6.37 x 10⁶ m)³/6.67 x 10⁻¹¹ N.m²/Kg²)(5.98 x 10²⁴ Kg)

T² = 1.02 x 10²² m³/3.99 x 10¹⁴ m³/s²

T² = 25,563,909.77 s²

T = 5,056.08 seconds    or around   1.4 Hour

3 0
3 years ago
Other questions:
  • The magnetic field over a certain range is given by B~ = Bx ˆı + By ˆ, where Bx = 2 T and By = 4 T. An electron moves into the
    10·1 answer
  • What distance formula
    15·1 answer
  • Difference between hair dryer and heat gun
    9·1 answer
  • In a crash or collision, why is it advantageous for an occupant to extend the time during which the collision is taking place?
    14·1 answer
  • The discovery of the Blombos cave suggests _________________
    9·2 answers
  • Select the correct answer. A credit union is a business that is owned by people who have something in common, offers you a place
    11·1 answer
  • Newton's first Law implies that an object at rest will remain at rest unlss a net force acts on it / TRUE or FALSE?
    14·1 answer
  • Please help. This question is urgent.​
    15·1 answer
  • Х
    10·1 answer
  • At the distance of Jupiter (6 times further away from the Sun than Earth) the amount of sunlight received per square centimeter
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!