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4 years ago

15

A night lamp uses a 30 W bulb. If it is left on continuously for 8 hours, how much energy will it use?

2 answers:

den301095 [7]4 years ago

6 0

Answer:

Explanation:

$30W * 8 h = 240 Wh = 0.240 kWh$

bezimeni [28]4 years ago

4 0

Answer:

0.24 kWh

Explanation:

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A basketball player jumps straight up with a speed of 14 m/s. How high did the player jump?

alexira [117]

Answer:

<em>The basketball player jumped 10 m high.</em>

Explanation:

<u>Vertical Launch Upwards </u>

In a vertical launch upwards, an object is launched vertically up without taking into consideration any kind of friction with the air.

If vo is the initial speed and g is the acceleration of gravity, the maximum height reached by the object is given by:

$\displaystyle h_m=\frac{v_o^2}{2g}$

The basketball player jumps up with a speed of vo=14 m/s. The maximum height is:

$\displaystyle h_m=\frac{14^2}{2*9.8}$

$\displaystyle h_m=\frac{196}{19.6}=10$

The basketball player jumped 10 m high.

7 0

3 years ago

A non-reflective coating that has a thickness of 198 nm (n = 1.45) is deposited on top of a substrate of glass (n = 1.50). What

spin [16.1K]

Answer:

The wavelength is $\lambda_ 1 = 574.2 nm$

Explanation:

From the question we are told that

The thickness is $t = 198 nm = 198 *10^{-9 }\ m$

The refractive index of the non-reflective coating is $n_m = 1.45$

The refractive index of glass is $n_g = 1.50$

Generally the condition for destructive interference is mathematically represented as

$2 * n_m * t * cos (\theta) = n * \lambda$

Where $\thata$ $\theta$ is the angle of refraction which is 0° when the light is strongly transmitted

and n is the order maximum interference

so

$\lambda = \frac{2 * n * t * cos (\theta )}{n}$

at the point n = 1

$\lambda _1 = \frac{2 * 1.45 * 198*10^{-9} * cos (0 )}{1}$

$\lambda_1 = 574.2 *10^{-9}$

$\lambda_1 = 574.2 nm$

at n =2

$\lambda _2 = \frac{\lambda _1 }{2}$

$\lambda _2 = \frac{574.2*10^{-9} }{2}$

$\lambda _2 = 2.87 1 *10^{-9} \ m$

$\lambda _2 = 287. 1 nm$

Now we know that the wavelength range of visible light is between

$390 \ nm \to 700 \ nm$

So the wavelength of visible light that is been transmitted is

$\lambda_ 1 = 574.2 nm$

6 0

4 years ago

Kelsey the triathelete swims 1.5 km east, then bikes 40 km north, and then runs 10 km west. Which choice gives the

Fittoniya [83]

Answer:

Hey,. its a simple question. hope you learn from the solution. check attached picture

Explanation:

3 0

3 years ago

If the thermometer reads 20° Celsius, what's the temperature in Fahrenheit? A. 52° B. 68° C. 72° D. 36°

Eduardwww [97]

The answer is B. 68°

6 0

3 years ago

An astronaut holds a rock 100 m above surface of Planet X. The rock is then thrown upwards with a sleek of 15m/s. The rock reach

Gelneren [198K]

Answer: $5 m/s^{2}$

Explanation:

This problem is related to vertical motion, and the equation that models it is:

$y=y_{o}+V_{o}sin\theta t-\frac{1}{2}gt^{2}$ (1)

Where:

$y=0m$ is the rock's final height

$y_{o}=100 m$ is the rock's initial height

$V_{o}=15 m/s$ is the rock's initial velocity

$\theta=90\°$ is the angle at which the rock was thrown (directly upwards)

$t=10 s$ is the time

$g$ is the acceleration due gravity in Planet X

Isolating $g$ and taking into account $sin(90\°)=1$ :

$g=(-\frac{2}{t^{2}})(y-y_{o}-V_{o}t)$ (2)

$g=(-\frac{2}{(10 s)^{2}})(0 m-100 m-(15 m/s)(10 s))$ (3)

$g=5 m/s^{2}$ (4) This is the acceleration due gravity in Planet X

5 0

3 years ago