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sammy [17]
3 years ago
14

A high-speed flywheel in a motor is spinning at 500 rpm when a power failure suddenly occurs. the flywheel has mass 40.0 kg and

diameter 76.0 cm . the power is off for 35.0 s and during this time the flywheel slows due to friction in its axle bearings. during the time the power is off, the flywheel makes 180 complete revolutions.
Physics
1 answer:
tangare [24]3 years ago
4 0
<span>The flywheel is solid cylindrical disc. Moment of inertial = ½ * mass * radius^2 Mass = 40.0 kg Radius = ½ * 76.0 cm = 38 cm = 0.38 meter Moment of inertial = ½ * 41 * 0.36^2 Convert rpm to radians/second The distance of 1 revolution = 1 circumference = 2 * π * r The number of radians/s in 1 revolution = 2 * π 1 minute = 60 seconds 1 revolution per minute = 2 * π radians / 60 seconds = π/30 rad/s Initial angular velocity = 500 * π/30 = 16.667 * π rad/s 170 revolutions = 170 * 2 * π = 340 * π radians The flywheel’s initial angular velocity = 16.667 * π rad/s. It decelerated at the rate of 1.071 rad/s^2 for 48.89 seconds. θ = ωi * t + ½ * α * t^2 θ = 16.667 * π * 48.89 + ½ * -1.071 * 48.89^2 2559.9 - 1280 θ = 1280 radians</span>
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I'm very confused. Thanks for whoever helps me :)
sergij07 [2.7K]
(C). Remember gravity provides an acceleration of 9.81m/s^2, so the y component of velocity initial is zero because it isn’t already falling, and we have the height, so basically we use the kinematic equation vf^2=vi^2+2ad, substitute given values and you get vf^2=2(9.81)(65) which is 1275, when you take the square root you get 35.7m/s for final velocity
(B). Then you use vf=vi+at to get the equation 35.7=(9.81)t, when you divide out you get 3.64s for time t
(A). Finally, since we assume that there is no acceleration or deceleration horizonatally, we just multiply the time taken for it to hit the ground and the initial speed ((3.64)(35.7)) to get 129.96, with significant figures I would round that to 130 metres.
**this is in the order that I felt was easiest to answer**
6 0
3 years ago
What property do the following elements have in common? Li, C, and F A) They are poor conductors of electricity. B) Each element
Aloiza [94]

Answer: Option (D) is the correct answer.

Explanation:

The given elements Li, C and F are all second period elements. So, when we move from left to right across a period then there occurs increase in number of valence electrons as there occurs increase in total number of electrons.

So, it means more electrons are added to the same energy level.

Thus, we can conclude that a property of valence electrons for each element is located in the same energy level is common in the given elements.

7 0
3 years ago
Read 2 more answers
What volume In liters is a cube 20cm on a side? If the cube is filled with water what is the mass of the water?
frez [133]
1 liter = 1000 cm^3
20cm * 20cm * 20cm = 8000 cm^3
8000/1000 = 8 liters

Since 1ml of water = 1 cm^3 = 1 grams
8 liters = 8000 grams = 8 kilograms
7 0
3 years ago
a stone is thrown horizonttaly from a cliff of a hill with an initial velocity of 30m/s it hits the ground at a horizontal dista
ELEN [110]

Answer:

a) Time = 2.67 s

b) Height = 35.0 m

Explanation:

a) The time of flight can be found using the following equation:

x_{f} = x_{0} + v_{0_{x}}t + \frac{1}{2}at^{2}   (1)

Where:

x_{f}: is the final position in the horizontal direction = 80 m

x_{0}: is the initial position in the horizontal direction = 0

v_{0_{x}}: is the initial velocity in the horizontal direction = 30 m/s

a: is the acceleration in the horizontal direction = 0 (the stone is only accelerated by gravity)

t: is the time =?  

By entering the above values into equation (1) and solving for "t", we can find the time of flight of the stone:  

t = \frac{x_{f}}{v_{0}} = \frac{80 m}{30 m/s} = 2.67 s

b) The height of the hill is given by:

y_{f} = y_{0} + v_{0_{y}}t - \frac{1}{2}gt^{2}

Where:

y_{f}: is the final position in the vertical direction = 0

y_{0}: is the initial position in the vertical direction =?

v_{0_{y}}: is the initial velocity in the vertical direction =0 (the stone is thrown horizontally)            

g: is the acceleration due to gravity = 9.81 m/s²

Hence, the height of the hill is:

y_{0} = \frac{1}{2}gt^{2} = \frac{1}{2}9.81 m/s^{2}*(2.67 s)^{2} = 35.0 m  

I hope it helps you!

5 0
3 years ago
The 25-mph zone is 150 yards long. How much time did the student save (in seconds) by speeding past the school
VikaD [51]

Answer:

Time = 12.27seconds

Explanation:

Given

Speed = 25miles/hour

Distance = 150 yards = 150(0.000568182)miles

Distance (in miles) = 0.0852273miles

Get the time

Speed = Distance/Time

Time = Distance/Speed

Time = 0.0852273/25

Time = 0.0034hours

Time = 0.0034 * 3600secs

Time = 12.27seconds

7 0
3 years ago
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