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Andrew [12]
3 years ago
11

how long does it take a 750watt heater operating at full rating to rais the temperature of 1kg of water From 40°C to 70°C {S.H.C

=4200j/kg/k and neglecte heat loss}​
Physics
1 answer:
siniylev [52]3 years ago
6 0

Answer:

168 seconds (2 min 48 s)

Explanation:

Find the heat absorbed by the water.

q = mCΔT

q = (1 kg) (4200 J/kg/K) (70°C − 40°C)

q = 126,000 J

Power is energy per time.

P = q / t

750 W = 126,000 J / t

t = 168 s

It takes 168 seconds (2 min 48 s).

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if the Horse and Rider have a combined mass of 572 kg what force would be required to accelerate them 5 kph per second
Vlad [161]

Answer:

   Force required to accelerate = 794.44 N

Explanation:

 Force required = Mass of horse x Acceleration of horse

 Mass of horse and rider, m=   572 kg

 Acceleration of horse and rider, a = 5 kph per second

                                      =\frac{5*1000}{60*60} =1.39 m/s^2

  Force required = ma

                             = 572 x 1.39 = 794.44 N

  Force required to accelerate = 794.44 N

8 0
3 years ago
A 3 kg rock sits on a 0.8 meter ledge. If it is pushed off, how fast will it be going at the bottom?
andrey2020 [161]

As long as it sits on the shelf, its potential energy
relative to the floor is . . .

   Potential energy =      (mass) x (gravity) x (height) =

                                       (3 kg) x (9.8 m/s²) x (0.8m) = <u>23.52 joules</u> .

If it falls from the shelf and lands on the floor, then it has exactly that
same amount of energy when it hits the floor, only now the 23.52 joules
has changed to kinetic energy.

   Kinetic energy =                                          (1/2) x (mass) x (speed)²

                                                 23.52 joules = (1/2) x (3 kg) x (speed)²

Divide each side by  1.5 kg :     23.52 m²/s² = speed²

Take the square root of each side:    speed = √(23.52 m²/s²) =  <em>4.85 m/s </em> (rounded)


6 0
3 years ago
Which of the following must be true about the object labeled X in the circuit below?
Alex787 [66]

the answer is c and if I help you  thank me
4 0
3 years ago
Provide one example of how Science drives Technology.
evablogger [386]

Answer:

Scientific knowledge is used to create new technologies. New technologies often allow scientists to explore nature in different ways and make new discoveries.

Explanation:

7 0
2 years ago
Read 2 more answers
The graph illustrates the activity level of three common digestive enzymes, across a range of pH values. Which enzyme is likely
vaieri [72.5K]

Answer:

(A) Pepsin

Explanation:

From the graph it is clear that pepsin is the only enzyme which works in highly acidic condintion in the digestive system.

  • less than 7 the liquid is acidic
  • above 7 the liquid is basic
  • at 7 the liquid is neutral

It has an optimum pH of about 1.5 at which its activity level is 8.5 as shown in graph.

7 0
3 years ago
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