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photoshop1234 [79]
2 years ago
12

5. How many kilowatt-hours of energy would be used by a 40 W bulb that runs for 10 hours every

Physics
1 answer:
Nady [450]2 years ago
6 0

Answer:

E = 0.4 kWh

Explanation:

Given that,

The power of a bulb, P = 40 W

Time, t = 10 hours

We need to find the energy used by the bulb. Let it is equal to E. So,

E=P\times t\\\\E=40\times 10\\\\E=400\ W-h\\\\or\\\\E=0.4\ kWh

So, 0.4 kWh of energy would be needed.

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What would the weight of an astronaut be on Saturn if his mass is 68 kg and acceleration of gravity on Saturn is 10.44 m/s2? Ple
alex41 [277]

Here's the part you need to know:

       (Weight of anything) =

                 (the thing's mass)
times
                 (acceleration of gravity in the place where the thing is) .

                 Weight = (mass ) x (gravity) .

That's always true everywhere.
You should memorize it.

For the astronaut on Saturn . . .

                   Weight = (mass ) x (gravity) .

                
  Weight =  (68 kg) x (10.44 m/s²)

                        
      =    709.92 newtons .
__________________________________

On Earth, gravity is only  9.8 m/s².
So as long as the astronaut is on Earth, his weight is only

                                   (68 kg) x (9.8 m/s²)

                               =    666.4 newtons .

Notice that his mass is his mass ... it doesn't change
no matter where he goes. 

But his weight changes in different places, because
it depends on the gravity in each place.

4 0
2 years ago
(Equation 17.6) Write the equation for the path-length difference at a bright fringe (constructive interference). Define all var
Andrews [41]

Answer:

  d sin tea = m λ

Explanation:

When we have a two-slit system, the optical path difference determines whether the intensity reaching an observation screen is maximum or zero.

To find this difference in optical path, we assume that the screen is much farther than the gap is, we draw a perpendicular from ray 1 to the second ray

       OP = d sin θ

now to have constructive interference and see a bright line this leg must be an integer number of wavelengths, ose

            d sin tea = m λ

where

d             is the distance between the two slits

θ     complexion the angle sea the point hold it between the two slits

λ    the wavelength of the coherent light used

m   an integer, which counts the number of lines of interference

Units in the SI system

d, lam in meters

θ degrees

m an integer

7 0
3 years ago
If only an external force can change the velocity of a body, how can the internal force of the brakes bring a car to rest? 1. It
RoseWind [281]

Answer:

4. It is the force of the road on the tires (an external force) that stops the car.

Explanation:

If there is no friction between the road and the tires, the car won't stop.

You can see this, for example, when there is ice on the road. You can still apply the brakes (internal force), but since there is no friction (external force) the car won't stop.

The force of the brakes on the wheels is not what makes the car stop, it is the friction of the road against still tires that makes it stop.

3 0
3 years ago
A helicopter starting on the ground is rising directly into the air at a rate of 25 ft/s. You are running on the ground starting
rusak2 [61]

Answer:

The rate of change of the distance between the helicopter and yourself (in ft/s) after 5 s is \sqrt{725} ft/ sec

Explanation:

Given:

h(t) =  25 ft/sec

x(t) = 10 ft/ sec

h(5) = 25 ft/sec . 5 = 125 ft

x(5) = 10 ft/sec . 5 = 50 ft

Now we can calculate the distance between the person and the helicopter by using the Pythagorean theorem

D(t) = \sqrt{h^2 + x^2}

Lets find the derivative of distance with respect to time

\frac{dD}{dt} (t)  = \frac{2h \cdot \frac{dh}{dt} +2x \cdot\frac{dx}{dt}} {2\sqrt{h^2 + x^2}}

Substituting the values of h(t) and  x(t) and simplifying we get,

\frac{dD}{dt}(t) = \frac{50t \cdot \frac{dh}{dt} + 20 \cdot \frac{dx}dt}{2\sqrt{625\cdot t^2 + 100 \cdot t^2}}

\frac{dh}{dt} = 25ft/sec

\frac{dx}{dt} = 10 ft/sec

\frac{Dd}{dt} (t) = \frac{1250t +200t}{2\sqrt{725}t}  = \frac{725}{\sqrt{725}}  = \sqrt{725} ft / sec

5 0
3 years ago
The first stage in the GAS model of stress is
Vladimir [108]
<span>The first stage in the Gas model of stress is alarm and mobilization. So the correct option in regards to the given question is option “d”. Hans Selye is the person that evolved this model and he has explained this model in complete details.  He has broken down his model into three stages. The first stage involves alarm and mobilization. The second stage includes resistance. The third and the final stage include the exhaustion stage. These are the stages that an organism goes through to restore back the balance when stress is exerted from outside. </span>


8 0
3 years ago
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