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Butoxors [25]
3 years ago
15

How much heat energy (in megajoules) is needed to convert 7 kg of ice at -9°C C to water at 0°C?

Physics
1 answer:
Molodets [167]3 years ago
5 0

Answer:

hence option A is correct

Explanation:

heat required from -9°C to 0°C ice = mass × specific heat of ice ×change in temperature

heat required from -9°C to 0°C ice = 7×2100×9 =132300 J =0.1323 MJ

( HERE SPECIFIC HEAT OF ICE IS A CONSTANT VALUE OF 2100

J/(kg °C )

heat required from  0°C ice to 0°C water = mass× specific heat of fusion of ice

                                                             = 7×3.36×10^5

                                                              = 2.352 × 10^6 J

                                                              = 2.352 MJ

TOTAL HEAT ENERGY REQUIRED = 0.1323 MJ +2.352 MJ

                                                          = 2.4843 MJ

hence option A is correct

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luda_lava [24]
Hope this helps you.

4 0
3 years ago
A person weighs 60 kg. The area under the foot of the person is 150 cm2. Find the pressure exerted on the ground by the person.
9966 [12]

Answer:

40000 N/m²

Explanation:

Applying,

P =  F/A................... Equation 1

Where P = Pressure, F = Force, A = Area.

From the question,

The force(F) exerted by the person's foot is thesame as it's weight.

F = W = mg............ Equation 2

Where m = mass of the person, g = acceleration due to gravity.

Substitute equation 2 into equation 1

P = mg/A................ Equation 3

Given: m = 60 kg, g = 10 m/s², A = 150 cm² = (150/10000) m² = 0.015 m²

Substitute these values into equation 3

P = (60×10)/0.015

P = 600/0.015

P = 40000 N/m²

3 0
3 years ago
The strength of an electromagnet CANNOT be increased by?
zmey [24]

Answer:

reversing the current

Explanation:

4 0
3 years ago
VERY EASY QUESTION!!!!!! 20 POINTS!!!!!!!!
slamgirl [31]
C. at a science fair
4 0
3 years ago
Read 2 more answers
A ball having a mass of 200 g is released from rest at a height of 400 mm above a very large fixed metal surface. If the ball re
AysviL [449]

Answer:

0.9

Explanation:

h = 400 mm, h' = 325 mm

Let the coefficient of restitution be e.

h' = e^2 x h

325 = e^2 x 400

e^2 = 0.8125

e = 0.9

5 0
3 years ago
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