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3 years ago

8

When you open the front door to your warm house on a cold day, which way does the heat flow? For example, which is correct to sa

y: "Close the door, you're letting the cold in!" or "Shut the door, you're letting the heat in!".

2 answers:

son4ous [18]3 years ago

7 0

Answer:

close the door your letting the cold in

sashaice [31]3 years ago

5 0

“Close the door, you’re letting the cold in!”

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1.If a nearsighted person has a far point df that is 3.50m from the eye, what is the focal length f1 of the contact lenses that

Alla [95]

Answer: a) -3.5m b) 0.22man

Explanation:

a) A near sighted person is a person that can only see near objects clearly but not far objects.

According to the lens formula

1/u+1/v = 1/f

where u = object distance (distance between the object and the lens)

v = image distance (distance between the image and the lens)

f = focal length of the lens

Given u= infinity v = 3.5m f= ?

1/f = 1/infinity +1/3.5

Since the lens used for correcting near sighted person is concave lens therefore the image distance is negative due to virtual image produced by the lens.

We then have 1/f1 = 1/infinity -1/3.5

f1 = -3.5m

b) A far sighted person is a person that can only see far objects clearly but not near objects.

According to the lens formula

1/u+1/v = 1/f

Given u= 0.35m v = 0.6m f2= ?

1/f2 = 1/0.35 + 1/0.6

Since the lens used for correcting far sighted person is convex lens therefore the image distance is positive due to mostly real image produced by the lens (reason why the image distance is positive.

f2 = 0.22m

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3 years ago

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An object moves in a straight line and is speeding up. Which one of the following statements is true?

kaheart [24]

I could be wrong on this one, but I think the answer is the first option, The net force on the object is in the direction of motion.

Friction can be acting on the object, but if the other force(s) that are acting on the object are greater, I think the object will still be able to accelerate.

The third option can't be true, according to Newton's second law $(f=ma)$ . If there were no forces acting on the object, or if the net forces cancelled each other out, the object wouldn't be accelerating unless its mass was changing.

I suppose the last option is also technically true, but the first is more specific..?

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(please help asap)

OLEGan [10]

Answer:

A. Yard

Explanation:

Should be correct lol :)

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if i got an C+ 77% in my science class but i got an 3 F's 0% recently on a science fair project, What will my grade go down to?

Crank

Your grade will probably go down to a D 68% or little higher than that

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A measurement that has both magnitude and direction

Korvikt [17]

<span>A measurement that both magnitude and direction is a vector quantity. An example of this is a moving car. The car exerts force due to its thrust and weight that runs in it. This will give us the magnitude of the car. The resulting motion of the car in terms of displacement, velocity and acceleration that determines its direction makes it a vector quantity. On the other hand, a measurement that has only magnitude is a scalar quantity. The energy exerted by the engine of the car is a scalar quantity.</span>

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