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
boyakko [2]
3 years ago
12

A DJ starts up her phonograph player. The turntable accelerates uniformly from rest, and takes t1 = 11.9 seconds to get up to it

s full speed of f1 = 78 revolutions per minute.
Case 2: The DJ then changes the speed of the turntable from f1 = 78 to f2 = 120 revolutions per minute. She notices that the turntable rotates exactly n2= 11 times while accelerating uniformly.

t1 = 11.9 seconds
n2 = 11 times

Part (a) Calculate the angular speed of the turntable while it is turning at f1 = 78 in radians/second in Case 1.

Part (b) How many revolutions does the turntable make while accelerating in Case 1?
Part (c) Calculate the magnitude of the angular acceleration of the turntable in Case 1, in radians/second2.
Part (d) Calculate the magnitude of the angular acceleration of the turntable (in radians/second2) while increasing to 120 RPM (Case 2).
Part (e) How long (in seconds) does it take for the turntable to go from f1 = 78 to f2 = 120 RPM?
Physics
1 answer:
Degger [83]3 years ago
4 0

Answer:

a)\omega_1=8.168\,rad.s^{-1}

b)n_1=7.735 \,rev

c)\alpha_1 =0.6864\,rad.s^{-2}

d)\alpha_2=4.1454\,rad.s^{-2}

e)t_2=1.061\,s

Explanation:

Given that:

  • initial speed of turntable, N_0=0\,rpm\Rightarrow \omega_0=0\,rad.s^{-1}
  • full speed of rotation, N_1=78 \,rpm\Rightarrow \omega_1=\frac{78\times 2\pi}{60}=8.168\,rad.s^{-1}
  • time taken to reach full speed from rest, t_1=11.9\,s
  • final speed after the change,  N_2=120\,rpm\Rightarrow \omega_2=\frac{120\times 2\pi}{60}=12.5664\,rad.s^{-1}
  • no. of revolutions made to reach the new final speed,  n_2=11\,rev

(a)

∵ 1 rev = 2π radians

∴ angular speed ω:

\omega=\frac{2\pi.N}{60}\, rad.s^{-1}

where N = angular speed in rpm.

putting the respective values from case 1 we've

\omega_1=\frac{2\pi\times 78}{60}\, rad.s^{-1}

\omega_1=8.168\,rad.s^{-1}

(c)

using the equation of motion:

\omega_1=\omega_0+\alpha . t_1

here α is the angular acceleration

78=0+\alpha_1\times 11.9

\alpha_1 = \frac{8.168 }{11.9}

\alpha_1 =0.6864\,rad.s^{-2}

(b)

using the equation of motion:

\omega_1\,^2=\omega_0\,^2+2.\alpha_1 .n_1

8.168^2=0^2+2\times 0.6864\times n_1

n_1=48.6003\,rad

n_1=\frac{48.6003}{2\pi}

n_1=7.735\, rev

(d)

using equation of motion:

\omega_2\,^2=\omega_1\,^2+2.\alpha_2 .n_2

12.5664^2=8.168^2+2\alpha_2\times 11

\alpha_2=4.1454\,rad.s^{-2}

(e)

using the equation of motion:

\omega_2=\omega_1+\alpha_2 . t_2

12.5664=8.168+4.1454\times t_2

t_2=1.061\,s

You might be interested in
What is kinematics?<br>explain!!~​<br><br>thankyou ~
Hatshy [7]

Answer:

<u>Kinematics:-</u>

  • Branch of mechanics concerned
  • Features of motion in an object
  • Causes and effects of motions

Hope it helps!

6 0
3 years ago
Read 2 more answers
I cant solve this problem, and our teacher said that this would be in the test we'll have tomorrow, can someone help me?
Ad libitum [116K]

Answer:

d = 11.1 m

Explanation:

Since the inclined plane is frictionless, this is just a simple application of the conservation law of energy:

\frac{1}{2} m {v}^{2}  = mgh

Let d be the displacement along the inclined plane. Note that the height h in terms of d and the angle is as follows:

\sin(15)  =  \frac{h}{d}  \\ or \: h = d \sin(15)

Plugging this into the energy conservation equation and cancelling m, we get

{v}^{2}  = 2gd \sin(15)

Solving for d,

d =  \frac{ {v}^{2} }{2g \sin(15) }  =  \frac{ {(7.5 \:  \frac{m}{s}) }^{2} }{2(9.8 \:  \frac{m}{ {s}^{2} })(0.259)}   \\ = 11.1 \: m

3 0
3 years ago
A wave is traveling at 241 m/s. It has a wavelength of 30.0 m. What is its frequency?
Feliz [49]

Answer:

A) 8.03Hz

Explanation:

f = V/λ

Where wavelength( λ )= 30m

Speed (V) =241m/S

f= 241/30=8.03Hz

3 0
3 years ago
a machine with a mechanical advantage of 2.5 requires an input force of 120 newtons. What output force is applied by this machin
creativ13 [48]
If your machine has a mechanical advantage of 2.5, then WHATEVER force you apply to the input, the force at the output will be 2.5 times as great.

If you apply 1 newton to the machine's input, the output force is

                 (2.5 x 1 newton)  =  2.5 newtons.

If you apply 120 newtons to the machine's input, the output force is

                 (2.5 x 120 newtons)  =  300 newtons.

4 0
3 years ago
A 540 kg satellite moves through deep space with a speed of 27 m/s. A booster rocket on the satellite fires for 1.4 s, giving a
prohojiy [21]

Answer: a

Explanation: because the answer is 1.4444444 and that's the closest

6 0
3 years ago
Read 2 more answers
Other questions:
  • The gravitational force between two objects is 3600 N. What will be the gravitational force between the objects if the mass of e
    14·1 answer
  • A rock is dropped from a third story window to the ground below. Assuming air resistance can be ignored, as it falls: a) only it
    10·1 answer
  • Clear cutting has a similar effect as controlled burning of a forest. <br><br> True<br><br> False
    6·2 answers
  • How long does it take for light from the sun to reach earth
    11·2 answers
  • A child pushes her toy across a level floor at a steady velocity of 0.50 m/s using an applied force of 2.0 N. If the weight of t
    5·2 answers
  • ou are to drive to an interview in another town, at a distance of 300 km on an expressway. The interview is at 11:15 a.m. You pl
    14·1 answer
  • Please help!!!!!!!!!!
    8·1 answer
  • 1. As the angle of the ramp is increased, the normal force increases /decreases / remains the same and the friction-force increa
    11·1 answer
  • 3. True or false. All objects that are made of metal<br> are magnetic. Explain why or why not.
    9·1 answer
  • The rubber band contains .......potential energy as it is stretched.
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!