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IRINA_888 [86]
2 years ago
9

What is the maximum velocity at which a 60-watt motor can lift an 8.5-kg mass upward?

Physics
1 answer:
enyata [817]2 years ago
3 0

Pick <em>choice-A</em> .

Weight of a mass = (mass) x (gravity)

Earth gravity = (9.8 m/s )

Weight of a mass = (9.8 x mass) Newtons

Work = (force) x (distance)

Power = (work done) / (time to do the work)

Weight of this mass = (8.5 kg) x ( 9.8 m/s ) = 83.3 Newtons

Work to lift it 1 meter = (83.3 N) x (1 m) = 83.3 Joules

Power to lift it 1 meter/sec = 83.3 Joule/sec = 83.3 watt

Power to lift it ' v ' meters/sec = 83.3v watts

In this problem ...

83.3 v watts = 60 watts

v =  60/83.3 m/s

<em>v =  0.72 m/s</em>

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8 0
3 years ago
An insulated beaker with negligible mass contains 0.250 kg of water at 75.0C. How many kilograms of ice at -20.0C must be droppe
kkurt [141]

Answer:

The amount of kilograms of ice at -20.0°C that must be dropped into the water to make the final temperature of the system 40.0°C = 0.0674 kg

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Total Heat gained by ice = Heat used by ice to move from -20°C to 0°C + Heat used to melt at 0°C + Heat used to reach 40°C from 0°C

To do this, we require the specific heat capacity of ice, latent heat of ice and the specific heat capacity of water. All will be obtained from literature.

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Heat gained by ice in taking the total temperature to 40°C = mCᵢ ΔT + mL + mC ΔT = m(2108)(0 - (-20)) + m(334000) + m(4186)(40 - 0) = 42160m + 334000m + 167440m = 543600 m

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543600 m = 36627.5

m = 0.0674 kg = 67.4 g of ice.

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3 years ago
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