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
givi [52]
3 years ago
15

Prior to the music CD, stereo systems had a phonographic turntable on which vinyl disk recordings were played. A particular phon

ographic turntable starts from rest and achieves a final constant angular speed of 33 1 3 rpm in a time of 4.5 s.
(a) How many rotations did the turntable undergo during that time?

(b) The classic Beatles album Abbey Road is 47 min and 7 s in duration. If the turntable requires 8 s to come to rest once the album is over, calculate the total number of rotations for the complete start-up, playing, and slow-down of the album.
Physics
1 answer:
mina [271]3 years ago
7 0

Answer: a) 1.3 rev. b) 1,573 rev.

Explanation:

Let's split the process in 3 phases: start-up, playing, and slow-down.

  • Start-Up

As the turntable starts from rest, ω₀ = 0.

If we choose θ₀ = 0º, assuming a constant angular acceleration, we can write the following expression for θ (in rads):

θ = 1/2  γ t² (1)

The angular acceleration γ, by definition is the rate of change of the angular velocity, so:

γ = ωf  - ω₀ / t . (2)

As ω₀ = 0, we can put the following:

γ = ωf / t

As we have ωf in rpm, it is advisable to convert it to rad/sec, as follows:

33 1/3 rpm (1 min/60 sec) . (2π rad/1 rev) = 111/100π rad/sec

Replacing in (2), we have:

γ = 37/150 π rad/sec²

Replacing in (1):

θ₁ = 999/400 π rad = 1.3 rev

  • Playing

During this phase, the turntable rotates at constant angular speed, so we can apply the definition of angular velocity to get the angle rotated, as follows:

θ₂ = ωf . t = (111/100)π . 2,827 sec = 313797/100 π rad = 1,569 rev.

  • Slow-down

Assuming a constant deceleration, as ωf = 0, we can find the value of the angular acceleration during this phase, as follows:

γ = -111/100 π / 8 rad/sec² = -0.44 rad/sec²

Now, we can apply the kinematic equation for the angle rotated under constant angular acceleration condition, as follows:

θ₃ = ω₀ t -1/2γ t²

Replacing by the values, we get:

θ₃ = 222/25 π - 111/25 π = 111/25 π rad = 2.2 rev

Adding the the three angles, we have:

θ = θ₁ + θ₂ + θ₃ = 1.3 + 1,569 + 2.2 = 1,573 rev

You might be interested in
What type of motion is shown with this graph? (5 points)
Vladimir [108]
It should be Constant speed. The line goes straight & doesn’t change within the graph.
7 0
3 years ago
It says find the slope for each line I'm stuck on number one can you help me
Allushta [10]
\text{slope}=\frac{y_2-y_1}{x_2-x_1}

(-2, -1)(3, 1)

Therefore,

\text{slope}=\frac{1-(-1)}{3-(-2)}=\frac{1+1}{3+2}=\frac{2}{5}

7 0
1 year ago
How much work is done in holding a 20 N sack of potatoes while waiting in line at the
Yuki888 [10]

Answer: A

Explanation:

honestly, it sounded the best

8 0
2 years ago
A steady beam of alpha particles (q = + 2e, mass m = 6.68 × 10-27 kg) traveling with constant kinetic energy 22 MeV carries a cu
cluponka [151]

Answer:

Explanation:

q = 2e = 3.2 x 10^-19 C

mass, m = 6.68 x 10^-27 kg

Kinetic energy, K = 22 MeV

Current, i = 0.27 micro Ampere = 0.27 x 10^-6 A

(a) time, t = 2.8 s

Let N be the alpha particles strike the surface.

N x 2e = q

N x 3.2 x 10^-19 = i t

N x 3.2 x 10^-19 = 0.27 x 10^-6 x 2.8

N = 2.36 x 10^12

(b) Length, L = 16 cm = 0.16 m

Let N be the alpha particles

K = 0.5 x mv²

22 x 1.6 x 10^-13 = 0.5 x 6.68 x 10^-27 x v²

v² = 1.054 x 10^15

v = 3.25 x 10^7 m/s

So, N x 2e = i x t

N x 2e = i x L / v

N x 3.2 x 10^-19 = 2.7 x 10^-7 x 0.16 / (3.25 x 10^7)

N = 4153.85

(c) Us ethe conservation of energy

Kinetic energy = Potential energy

K = q x V

22 x 1.6 x 10^-13 = 2 x 1.5 x 10^-19 x V

V = 1.17 x 10^7 V

5 0
3 years ago
The Escape speed at the surface of a certain planet is twice that of the earth. what is its mass in unit of earth's mass?
VLD [36.1K]

Answer:

22Km/sec

Explanation:

6 0
2 years ago
Other questions:
  • What unit is used to express work?
    8·1 answer
  • Laticia draws the diagram below to show Earth’s magnetic field.
    15·2 answers
  • Which characteristics is common in mature rivers river
    7·2 answers
  • spring is compressed 4.2 cm. If a box is placed at the end of the compressed spring, and let go, how far up the ramp will the sp
    7·1 answer
  • Do you wont to be friends
    9·1 answer
  • Thunder and lightning may become connected in the mind because they often occur together. This is an example of which of the fol
    14·2 answers
  • What’s the surface temperature of earth
    10·1 answer
  • A 100kg car travels at 2m/s. what is the momentum in kg
    7·1 answer
  • John attached a ball to a spring
    13·1 answer
  • 8. As you throw a 2.00 x 102 g baseball, your hand moves a distance of 80.0 cm before you release the ball. If you exert an aver
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!