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3 years ago

The light from the Sun heats a metal surface. This is an example of what?

2 answers:

8 0

Radiation. That's perhaps the only way that energy gets from the Sun to the earth. The space between the two is a vacuum, so conduction is more or less out as is convection. There's no obvious sign of mirrors, so reflection seems to be out as well.

tekilochka [14]3 years ago

5 0

Answer: The correct answer is radiation.

Explanation:

There are three method of transfer of energy: conduction, convection and radiation.

In conduction, there is no actual movement of the particle. There is conduction in the solid. Heat is transferred from hotter end of an object to cold end of the particle.

In convection, there is actual movement of the particle. Both liquid and gases can transfer heat energy by convection.

In radiation, it does not require particles in its transfer of energy. In the given problem, the light from the Sun heats a metal surface. This is an example of radiation.

Therefore, the option is A.

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The majority of water on Earth exists as salt water, and only a very small percentage exists as fresh water. More than half of t

serg [7]

Answer:

B Crystallization

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2 years ago

A solar cooker, really a concave mirror pointed at the sun, focuses the sun's rays 16.0 cm in front of the mirror. what is the r

VARVARA [1.3K]

The focal point of a concave mirror is halfway along the radius, therefore the radius would be 2•16= 32 cm

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3 years ago

1. Calculate the charge in a circuit which carries a current of 30 amperes for 5 seconds

sweet-ann [11.9K]

Answer:

1. 150C.

2. 50sec

3.1.5a

Explanation:

1. I = Q/T

Q= 30x5

=150c

2.applying the formulae, I = Q/T

T= Q/I

=500/10

=50sec.

3. using the formulae i=q/t

i= 120/80

=1.5a.

6 0

3 years ago

If the average pitcher is releasing the ball from a height of 1.8 m above the ground, and the pitcher's mound is 0.2 m higher th

mina [271]

The catcher can catch the ball at a height of 0.96 m from the ground.

The distance between the pitcher's mound and the catcher's box is about 60'6", which translates to 18.44 m. An average pitcher can pitch with speeds ranging from 88 mph to 97 mph, which is from 39.3 m/s to 43.4 m/s.

Assume the pitcher pitches a ball horizontally with a speed of 40 m/s. If the catcher catches the ball in a time t, then the ball travels a horizontal distance x of 18.44 m and at the same time falls through a height y.

The horizontal motion of the ball is uniform motion since no force acts on the ball ( assuming no air resistance) and hence the acceleration of the ball along the horizontal direction is zero.

Therefore,

$x=ut$

Calculate the time t by substituting 18.44 m for x and 40 m/s for u.

$t=\frac{x}{u} \\ =\frac{18.44 m}{40 m/s} \\ =0.461s$

The ball is acted upon by the earth's gravitational attraction and hence it accelerates downwards with an acceleration equal to the acceleration due to gravity g.

Since a horizontal projection is assumed, the ball has no component of velocity in the downward direction.

Therefore, for vertical motion, which is an accelerated motion, the distance y, the ball falls in the time t taken by it to reach the catcher's box is given by the equation,

$y=\frac{1}{2} gt^2$

Substitute 9.8 m/s² for g and 0.461 s for t.

$y=\frac{1}{2} gt^2\\ y=\frac{1}{2}(9.8 m/s^2)(0.461s)^2=1.04 m$

The pitcher releases the ball at a height of 1.8 m from a mound which is at a height of 0.2 m. Thus, the ball is released at a height of 2.0 m from the ground. It falls through a distance of 1.04 m in the time it takes to reach the catcher.

Therefore, the height at which the catcher needs to keep his glove so as to catch the ball is given by, $(2.0 m)-(1.04 m)=0.96 m$

The catcher needs to hold his glove at a height of <u>0,96 m from the ground.</u>

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3 years ago

A transformer has a primary coil with 600 turns and a secondary coil

Lostsunrise [7]

Number of turns in the primary Np = 600
Number of turns in the secondary Ns = 300
Output voltage Es = 320 volts
Input voltage Ep = ?
Assuming the transformer to be ideal,
Np/Ns = Ep/Es
Ep/Es = 600/300 = 2
<span>Ep = 320*2 = 640 volts </span>

6 0

3 years ago