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2 years ago

14

The human eye has two lenses. O true O False

2 answers:

Bad White [126]2 years ago

8 0

Answer:

true its truedjjs sjsnsns

Rama09 [41]2 years ago

6 0

True I love you and I’m not going on a trip with

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An ideal heat engine absorbs 97.2 kJ of heat and exhausts 83.8 kJ of heat in each cycle. What is the efficiency of the engine?

r-ruslan [8.4K]

Answer:

13.7%

Explanation:

Given that,

Heat absorbed by the engine = 97.2 kJ

Heat exhausted by the engine in each cycle = 83.8 kJ

We need to find the efficiency of the engine. It is calculated by the formula.

$\eta=1-\dfrac{Q_e}{Q_a}\\\\=1-\dfrac{83.8}{97.2}\\\\=0.137\\\\=13.7\%$

so, the efficiency of heat engine is 13.7%.

5 0

3 years ago

A rock is projected upward from the surface of the moon, at time t = 0.0 s, w a velocity of 30 m/s. The acceleration due to grav

Vinvika [58]

<h2>Answer: 277.777 m</h2>

Explanation:

The situation described here is parabolic movement. However, as we are told that the rock was<u> projected upward from the surface</u>, we will only use the equations related to the Y axis.

In this sense, the movement equations in the Y axis are:

$y-y_{o}=V_{o}.t+\frac{1}{2}g.t^{2}$ (1)

$V=V_{o}-g.t$ (2)

Where:

$y$ is the rock's final position

$y_{o}=0$ is the rock's initial position

$V_{o}=30\frac{m}{s}$ is the rock's initial velocity

$V$ is the final velocity

$t$ is the time the parabolic movement lasts

$g=1.62\frac{m}{s^{2}}$ is the acceleration due to gravity at the surface of the moon

As we know $y_{o}=0$ , equation (2) is rewritten as:

$y=V_{o}.t+\frac{1}{2}g.t^{2}$ (3)

On the other hand, the maximum height is accomplished when $V=0$ :

$V=V_{o}-g.t=0$ (4)

$V_{o}-g.t=0$

$V_{o}=g.t$ (5)

Finding $t$ :

$t=\frac{V_{o}}{g}$ (6)

Substituting (6) in (3):

$y=V_{o}(\frac{V_{o}}{g})+\frac{1}{2}g(\frac{V_{o}}{g})^{2}$ (7)

$y_{max}=\frac{{V_{o}}^{2}}{2g}$ (8) Now we can calculate the maximum height of the rock

$y_{max}=\frac{{(30m/s)}^{2}}{(2)(1.62m/s^{2})}$ (9)

Finally:

$y_{max}=277.777m$

4 0

2 years ago

It took David 2 seconds to lift a 5 Newton bag of toys from the floor to the top of the top shelf, which is 3 meters tall. How m

just olya [345]

So power is equal to work over time and work is force times distance, you do 5 times 3 and get 15 dividing by 2 gives us 7.5 W answer c

7 0

2 years ago

A contestants spin a wheel when it is their turn in a game show. One contestant gives the wheel an initial angular speed of 3.40

guajiro [1.7K]

Answer:

4.62 s

Explanation:

We are given that

Initial angular speed, $\omega=3.4 rad/s$

$\theta=1\frac{1}{4} rev=\frac{5}{4}\times 2\pi=2.5\pi rad$

$\omega'=0$

$\omega'^2-\omega^2=2\alpha \theta$

Substitute the values

$0-(3.4)^2=2\times 2.5\pi \alpha$

$\alpha=\frac{-(3.4)^2}{2\times 2.5\pi}=-0.736 rad/s^2$

$\omega'=\omega+\alpha t$

$0=3.4-0.736 t$

$-0.736t=-3.4$

$t=\frac{-3.4}{-0.736}=4.62 s$

Hence, the wheel takes 4.62 s to come to rest.

3 0

3 years ago

A person covers a distance of 320 miles in a travel time of 8 hours. What is the speed for this trip?

goldfiish [28.3K]

Take 320 and divide by 8
320/8 = 40 mi/hr or A

8 0

3 years ago

Read 2 more answers