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nevsk [136]
3 years ago
12

A motor running at 2600 rev/min is suddenly switched off and decelerates uniformly to rest after 10 s. Find the angular decelera

tion and the number of rotations to come to rest?
Physics
1 answer:
Mama L [17]3 years ago
6 0
Angular acceleration = (change in angular speed) / (time for the change)

change in angular speed = (zero - 2,600 RPM)  =  -2,600 RPM

time for the change = 10 sec

Angular acceleration = -2600 RPM / 10 sec = -260 rev / min-sec

(-260 rev/min-sec) x (1 min / 60 sec) = <em>-(4 1/3)  rev / sec²</em>

Since the acceleration is negative, the motor is slowing down.
You might call that a 'deceleration' of (4 1/3) rev/sec² .

The average speed is  1/2(2,600 + 0) = 1,300 rev/min = (21 2/3) rev/sec.

Number of revs = (average speed) x (time) = (21 2/3) x (10sec) = <em>(216 2/3) revs</em>
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4 0
3 years ago
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Why to astronauts appear weightless while they are filmed performing activities inside the orbiting space shuttle?
vagabundo [1.1K]
<h2>Answer: The astronauts are falling at the same rate as the space shuttle as it orbits around earth</h2>

The astronauts seem to float because they are in free fall just like the spacecraft.

However, although they are constantly falling on the Earth, they do not fall because the ship orbits at a sufficient speed (in the same direction of rotation of the Earth) so that the centrifugal force is balanced with the Earth's gravitational pull.

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8 0
3 years ago
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2. A 0.8 kg tetherball hangs on the end of a cord. It is hit by a child and rises 2.1 m above the ground. a. What is the maximum
skad [1K]

Answer:

E = 16.464 J

Explanation:

Given that,

Mass of tetherball, m = 0.8 kg

It is hit by a child and rises 2.1 m above the ground, h = 21. m

We need to find the maximum gravitational potential energy of the ball. The formula for the gravitational potential energy is given by :

E = mgh

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E = 0.8 kg × 9.8 m/s² × 2.1 m

= 16.464 J

So, the maximum potential energy of the ball is 16.464 J.

3 0
3 years ago
Malcolm and Ravi raced each other. The average of their maximum speeds was 260 km/h If doubled, Malcolm's maximum speed would be
AfilCa [17]

Answer

Given,

Average speed of Malcolm and Ravi = 260 km/h

Let speed of the Malcolm be X and speed of the Ravi Y.

From the given statement

\dfrac{X+Y}{2}=260

X + Y = 520 ....(i)

2X - Y = 80  ....(ii)

Adding both the equations

3 X = 600

 X = 200 km/h

Putting value in equation (i)

Y = 520 - 200

Y = 320 Km/h

Speed of Malcolm = 200 Km/h

Speed of Ravi = 320 Km/h

8 0
3 years ago
Unpolarized light passes through two polarizers whose transmission axes are at an angle # with respect to each other. What shoul
Yuki888 [10]

Answer:

63.4^{\circ}

Explanation:

When unpolarized light passes through the first polarizer, the intensity of the light is reduced by a factor 1/2, so

I_1 = \frac{1}{2}I_0 (1)

where I_0 is the intensity of the initial unpolarized light, while I_1 is the intensity of the polarized light coming out from the first filter. Light that comes out from the first polarizer is also polarized, in the same direction as the axis of the first polarizer.

When the (now polarized) light hits the second polarizer, whose axis of polarization is rotated by an angle \theta with respect to the first one, the intensity of the light coming out is

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If we combine (1) and (2) together,

I_2 = \frac{1}{2}I_0 cos^2 \theta (3)

We want the final intensity to be 1/10 the initial intensity, so

I_2 = \frac{1}{10}I_0

So we can rewrite (3) as

\frac{1}{10}I_0 =  \frac{1}{2}I_0 cos^2 \theta

From which we find

cos^2 \theta = \frac{1}{5}

cos \theta = \frac{1}{\sqrt{5}}

\theta=cos^{-1}(\frac{1}{\sqrt{5}})=63.4^{\circ}

6 0
3 years ago
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