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Klio2033 [76]
4 years ago
7

a 4lb ball is travelling in a circle radius 3ft speed 6ft/s. the attached cord pulled through the center has constant speed 2ft/

s. how much time for the ball to reach 12 ft/s
Physics
1 answer:
lora16 [44]4 years ago
4 0

Answer:

Explanation:

Circle motion

Weight=4lb

Radius=3ft

Velocity Vb= 6ft/s

Velocity Vr=2ft/s

Velocity Vo=12

V2=√Vo²+Vr²

12=√Vo²+2²

Square both side

144=Vo²+4

Vo²=140

Vo=11.83ft/s

Applying conservation of angular momentum

Ha1=Hb2

MbVbr1=MbVor2

r2=Vbr1/Vo

r2=6×3/11.83

r2=1.52ft

The require time is written as.

∆r=Vrt

t=∆r/Vr

t=r1-r2/Vr

t=3-1.52/2

t=0.74sec

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Final velocity = 0, thus final kinetic energy is 0
Initial kinetic energy:
0.5mv²
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= 4.0 J
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5 0
3 years ago
A single-turn circular loop of wire of radius 45 mm lies in a plane perpendicular to a spatially uniform magnetic field. During
Lina20 [59]

Answer:

Magnitude of induced emf is 0.00635 V

Explanation:

Radius of circular loop r = 45 mm = 0.045 m

Area of circular loop A=\pi r^2

A=3.14\times 0.045^2=0.00635m^2

Magnetic field is increases from 250 mT to 350 mT

Therefore change in magnetic field dB=250-350=100mT

Emf induced is given by

e=-N\frac{d\Phi }{dt}=-NA\frac{dB}{dt}

e=-0.00635\times \frac{100\times 10^{-3}}{0.10}=-0.00635V

Magnitude of induced emf is equal to 0.00635 V

7 0
3 years ago
Average human body temperature is 98.6°F. What is the equivalent in degrees Celsius?
Gala2k [10]

37° Celsius is equal to 98.6° Fahrenheit

6 0
3 years ago
If a thermometer measured the temperature in an oven as 400oF five days in a row when the temperature was actually 397oF, this m
aleksandrvk [35]

Answer:

It can be said to be reliable although it is not valid

Explanation:

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5 0
3 years ago
How fast must an object move before its length appears to be contracted to one-fourth its proper length? (Give your answer in te
Tresset [83]

Answer:

<em>0.97c</em>

<em></em>

Explanation:

From the relativistic equation for length contraction, we have

l = l_{0}\sqrt{1 - \beta }

where

l is the final length of the object

l_{0} is the original length of the object before contraction

β = v^{2} /c^2

where v is the speed of the object

c is the speed of light in free space = 3 x 10^8 m/s

The equation can be re-written as

l/l_{0} = \sqrt{1 - \beta }

For the length to contract to one-fourth of the proper length, then

l/l_{0} = 1/4

substituting into the equation, we'll have

1/4 = \sqrt{1 - \beta }

substituting for β, we'll have

1/4 = \sqrt{1 - v^2/c^2 }

squaring both side of the equation, we'll have

1/16 = 1 - v^2/c^2

v^2/c^2 = 1 - 1/16

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square root both sides of the equation, we have

v/c = 0.968

v = <em>0.97c</em>

3 0
3 years ago
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