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2 years ago

Kayla drew a diagram to compare convex and concave lenses which labels belong in the areas marked XYZ

Physics

1 answer:

lesya692 [45]2 years ago

8 0

Answer:

X: Causes light rays to bend toward the principal axis

Y: Is capable of producing images that are smaller than objects

Z: Causes light rays to bend away from the principal axis

Explanation:

just took the test...

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With full explaniation

zzz [600]

A. The ball's (vertical) velocity $v$ at time $t$ is

$v(t) = 30\dfrac{\rm m}{\rm s} - gt$

so that after 4 seconds, the ball's speed is

$|v(4\,\mathrm s)| = \left|30\dfrac{\rm m}{\rm s} - \left(10\dfrac{\rm m}{\mathrm s^2}\right) (4\,\mathrm s)\right| = \boxed{10\frac{\rm m}{\rm s}}$

(The velocity is -10 m/s, so the ball is falling back down at this point.)

B. At maximum height, the ball has zero velocity, so it takes

$30\dfrac{\rm m}{\rm s} - gt = 0 \implies t = \dfrac{30\frac{\rm m}{\rm s}}g = \boxed{3\,\mathrm s}$

for the ball to reach this height.

C. The height of the ball $y$ at time $t$ is

$y(t) = \left(30\dfrac{\rm m}{\rm s}\right) t - \dfrac g2 t^2$

The maximum height is attained by the ball at 3 seconds after it's thrown, so

$y_{\rm max} = \left(30\dfrac{\rm m}{\rm s}\right) (3\,\mathrm s) - \dfrac{10\frac{\rm m}{\mathrm s^2}}2 (3\,\mathrm s)^2 = \boxed{45\,\mathrm m}$

D. The time it takes for the ball to reach its maximum height is half the time it spends in the air. So the total airtime is $\boxed{6\,\mathrm s}$ .

Put another way: When the ball returns to the height from which it was thrown, its final velocity has the same magnitude as its initial velocity but points in the opposite direction. This is to say, after the total time the ball is in the air, it's final velocity will be -30 m/s. Then the total airtime is

$30\dfrac{\rm m}{\rm s} - gt = -30\dfrac{\rm m}{\rm s} \implies t = \dfrac{60\frac{\rm m}{\rm s}}g = \boxed{6\,\mathrm s}$

Put yet another way: Solve $y(t) = 0$ for $t$ . I don't see a need to elaborate...

5 0

2 years ago

A 0.4 kg ball is thrown straight up into the air with a velocity of 12.2 m/s. What maximum height will it reach?

AysviL [449]

Answer:

Maximum height is 7.59 m.

Explanation:

We have,

Mass of a ball is 0.4 kg

It is thrown straight up into the air with a velocity of 12.2 m/s.

It is required to find the maximum height reached by the ball.

Concept used : Law of conservation of energy.

Solution,

Here, the energy of the ball remains conserved. Let h is the maximum height reached by the ball such that,

$\dfrac{1}{2}mv^2=mgh\\\\h=\dfrac{v^2}{2g}\\\\h=\dfrac{(12.2)^2}{2\times 9.8}\\\\h=7.59\ m$

So, the maximum height reached by the ball is 7.59 m.

6 0

3 years ago

Identify the arrows that show input force

satela [25.4K]

The answer is that the reverse arrows pointing to the left needs to release energy. The molecules in the gas state are free such that they can travel from one point to another easily. They have the highest amount of energy. So, if you want the molecules to come closer together, you need to remove the energy to keep them in place. Therefore, the arrows pointing to the right require removal of energy.

8 0

2 years ago

Time is relative, what does that mean?

lord [1]

<span>It means that the passage of time changes in different reference frames that are moving relative to each other. </span>

5 0

2 years ago

The rear window of a van is coated with a layer of ice at 0Â°c. the density of ice is 917 kg/m3, and the latent heat of fusion o

seraphim [82]

Let h = the thickness of ice, m.

Because the ice covers an area of 0.65 m², the volume of ice is
V = 0.65h m³

The density of ice is 917 kg/m³, therefore the mass of ice is
m = (917 kg/m³)*(0.65h m³) = 596.05h kg

The latent heat of fusion of ice is 3.35 x 10⁵ J/kg, therefore the heat required to melt the ice is
Q₁ = (596.05h kg)*(3.35 x 10⁵ J/kg) = 2h x 10⁸ J

The electric heater supplies heat at 12 V, 23 A for 4.3 minutes to melt the ice.
Therefore the heat provided is
Q₂ = (12 V)*(23 A)*(4.3*60 s) = 71208 J

Because Q₁ = Q₂, obtain
2h x 10⁸ = 71208
h = 356 x 10⁻⁶ m = 356 x 10⁻³ mm = 0.356 mm

Answer: 0.356 mm

3 0

3 years ago