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charle [14.2K]
3 years ago
9

A propeller is modeled as five identical uniform rods extending radially from its axis. The length and mass of each rod are 0.71

5 m0.715 m and 2.51 kg2.51 kg , respectively. When the propellor rotates at 527 rpm527 rpm (revolutions per minute), what is its rotational kinetic energy?
Physics
1 answer:
Rainbow [258]3 years ago
3 0

Answer:

3260.33 J

Explanation:

n  = number of rods = 5

L  = length of each rod = 0.715 m

m  = mass of rod = 2.51 kg

I  = total moment of inertia

Total moment of inertia is given as

I = \frac{nmL^{2}}{3}

I = \frac{(5)(2.51)(0.715)^{2}}{3}

I = 2.14 kgm²

w  = angular speed = 527 rpm = 55.2 rad/s

Rotational kinetic energy is given as

E = (0.5) I  (w )²

E = (0.5) (2.14) (55.2)²

E = 3260.33 J

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An electron is accelerated by a 3.6 kv potential difference. the charge on an electron is 1.60218 × 10−19 c and its mass is 9.10
katen-ka-za [31]
By definition, the potential energy is:
 U = qV
 Where,
 q: load
 V: voltage.
 Then, the kinetic energy is:
 K = mv ^ 2/2
 Where,
 m: mass
 v: speed.
 As the power energy is converted into kinetic energy, we have then:
 U = K
 Equating equations:
 qV = mv ^ 2/2
 From here, we clear the speed:
 v = root (2qV / m)
 Substituting values we have:
 v = root ((2 * (1.60218 × 10 ^ -19) * 3600) /9.10939×10^-31))
 v = 3.56 × 10 ^ 7 m / s
 Then, the centripetal force is:
 Fc = Fm
 mv ^ 2 / r = qvB
 By clearing the magnetic field we have:
 B = mv / qr
 Substituting values:
 B = (9.10939 × 10 ^ -31) * (3.56 × 10 ^ 7) / (1.60218 × 10 ^ -19) * 0.059
 B = 3.43 × 10 ^ -3 T
 Answer:
 
A magnetic field that must be experienced by the electron is:
 
B = 3.43 × 10 ^ -3 T
6 0
3 years ago
1. A television set falls from rest from a bridge 100m above the river surface.
Stolb23 [73]

Answer:

It would break because how fast and how tall the fall is because at a certain hight water can act like a solid and break your body/bones or you could die

its a do or die situation

Explanation:

3 0
3 years ago
The concentration of Biochemical Oxygen Demand (BOD) in a river just downstream of a wastewater treatment plant’s effluent pipe
shtirl [24]

Answer:

The BOD concentration 50 km downstream when the velocity of the river is 15 km/day is 63.5 mg/L

Explanation:

Let the initial concentration of the BOD = C₀

Concentration of BOD at any time or point = C

dC/dt = - KC

∫ dC/C = -k ∫ dt

Integrating the left hand side from C₀ to C and the right hand side from 0 to t

In (C/C₀) = -kt + b (b = constant of integration)

At t = 0, C = C₀

In 1 = 0 + b

b = 0

In (C/C₀) = - kt

(C/C₀) = e⁻ᵏᵗ

C = C₀ e⁻ᵏᵗ

C₀ = 75 mg/L

k = 0.05 /day

C = 75 e⁻⁰•⁰⁵ᵗ

So, we need the BOD concentration 50 km downstream when the velocity of the river is 15 km/day

We calculate how many days it takes the river to reach 50 km downstream

Velocity = (displacement/time)

15 = 50/t

t = 50/15 = 3.3333 days

So, we need the C that corresponds to t = 3.3333 days

C = 75 e⁻⁰•⁰⁵ᵗ

0.05 t = 0.05 × 3.333 = 0.167

C = 75 e⁻⁰•¹⁶⁷

C = 63.5 mg/L

5 0
3 years ago
You use 350 W of power to move a 7.0 N object 5 m.<br> How long did it take?
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Answer:

0.1 second

Explanation:

We are given;

Power; P = 350 W

Force; F = 7 N

Distance; d = 5 m

Formula for power is;

P = workdone/time taken

Workdone = F × d

Thus;

350 = (7 × 5)/t

t = 35/350

t = 0.1 second

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