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Sedaia [141]
3 years ago
11

An engine exhausts 1140 j of energy for every 3790 j of energy it takes in. what is its efficiency?

Physics
1 answer:
densk [106]3 years ago
6 0
Given:\\ Q_+=3790J\\Q_-=1140J\\\\Find:\\\eta=?\\\\Solution:\\\\\eta=1- \frac{Q_-}{Q_+} \\\\\eta=1- \frac{1140J}{3790J} \approx 0.7
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What traction of the radioisotope<br>remains in the body after one day?​
r-ruslan [8.4K]

The fraction of radioisotope left after 1 day is (\frac{1}{2})^{\frac{1}{\tau}}, with the half-life expressed in days

Explanation:

The question is incomplete: however, we can still answer as follows.

The mass of a radioactive sample after a time t is given by the equation:

m(t)=m_0 (\frac{1}{2})^{\frac{t}{\tau}}

where:

m_0 is the mass of the radioactive sample at t = 0

\tau is the half-life of the sample

This means that the mass of the sample halves after one half-life.

We can rewrite the equation as

\frac{m(t)}{m_0}=(\frac{1}{2})^{\frac{t}{\tau}}

And the term on the left represents the fraction of the radioisotope left after a certain time t.

Therefore, after t = 1 days, the fraction of radioisotope left in the body is

\frac{m(1)}{m_0}=(\frac{1}{2})^{\frac{1}{\tau}}

where the half-life \tau must be expressed in days in order to match the units.

Learn more about radioactive decay:

brainly.com/question/4207569

brainly.com/question/1695370

#LearnwithBrainly

5 0
3 years ago
A juggler throws a bowling pin straight up with an initial speed of 8.20 m/s. How much time elapses until the bowling pin return
tensa zangetsu [6.8K]

Answer:

1.68 s

Explanation:

From newton's equation of motion,

a = (v-u)/t.................................. Equation 1

Making t the subject of the equation

t =(v-u)g............................. Equation 2

Where t = time taken for the bowling pin to reach the maximum height, v = final velocity bowling pin, u = initial velocity of the bowling pin, g = acceleration due to gravity.

Note: Taking upward to be negative and down ward to be positive,

Given: v = 0 m/s ( at the maximum height), u = 8.20 m/s, g = -9.8 m/s²

t = (0-8.20)/-9.8

t = -8.20/-9.8

t = 0.84 s.

But,

T = 2t

Where T = time taken for the bowling pin to return to the juggler's hand.

T = 2(0.84)

T = 1.68 s.

T = 1.68 s

7 0
3 years ago
A wave with a frequency of 14 Hz has a wavelength of 7m. At what speed will this wave travel?
frutty [35]

Answer: A wave with a frequency of 14 Hz has a wavelength of 3 meters. At what speed will this wave travel? 1. = 3m (4. = 42m. 2. ... 1,7m (46) = 7802 m. 4. A wave traveling at 230 m/sec has a wavelength of 2.1 meters. What is the frequency of.

Explanation: please give me brainlest

8 0
3 years ago
What causes irregular galaxies to be irregular
Mariulka [41]

Irregular galaxies get their odd shapes in many ways. One way irregular galaxies are formed is when galaxies collide or come close to one another, and their gravitational forces interact. Another source of irregular galaxies may be very young galaxies that have not yet reached a symmetrical state.

8 0
3 years ago
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A cart travels down a ramp at an average speed of 5.00 centimeters/second. What is the speed of the cart in miles/hour? (Remembe
viva [34]
Set up the problem with the conversion rates as fractions where when you multiply the units cancel out leaving the desired units behind.

( \frac{ 5 cm}{1 sec} ) *( \frac{1m }{100cm})*( \frac{1km}{1000m} )*( \frac{1mi}{1.6km} ) = 0.00003125 mi/sec \\  \\ ( \frac{0.00003125 mi}{1sec} )*( \frac{60sec}{1min} )*( \frac{60min}{1hr} )=0.1125 mi/hr
7 0
3 years ago
Read 2 more answers
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