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3 years ago

8

If a heat engine pulls 4390.0 J of heat from the hot reservoir and exhausts 3582.2 J of heat to the cold reservoir, what was the

work done by the engine? What is the efficiency of this engine in percent? (do not enter the percent sign)

1 answer:

Oksanka [162]3 years ago

8 0

Answer:

18.4

Explanation:

Q1 = 4390 J

Q2 = 3582.2 J

The efficiency of heat engine is given by

n = 1 - Q2 / Q1

n = 1 - 3582.2 / 4390

n = 0.184

n = 18.4 %

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In a ballistics test, a 24 g bullet traveling horizontally at 1200 m/s goes through a 31-cm-thick 320 kg stationary target and e

Zanzabum

Answer:

The velocity is $v_t = 0.02175 \ m/s$

Explanation:

From the question we are told that

The mass of the bullet is $m_b = 0.024 \ kg$

The initial speed of the bullet is $u_b = 1200 \ m/s$

The mass of the target is $m_t = 320 \ kg$

The initial velocity of target is $u_t = 0 \ m/s$

The final velocity of the bullet is is $v_b = 910 \ m/s$

Generally according to the law of momentum conservation we have that

$m_b * u_b + m_t * u_t = m_b * v_b + m_t * v_t$

=> $0.024 * 1200 + 320 * 0 = 0.024 * 910 + 320 * v_t$

=> $v_t = 0.02175 \ m/s$

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4 years ago

You're driving down the highway late one night at 20 m/s when a deer steps onto the road 49 m in front of you. You reaction time

Leno4ka [110]

Answer:

v = 26.7 m/s

Explanation:

Given,

speed of the car = 20 m/s

distance between the car and the deer = 49 m

time taken to press the brake = 0.50 s

maximum deceleration of the car = 10 m/s²

Now,

distance travel by the car in 0.5 s = u x t = 20 x 0.5 = 10 m

distance travel by the car after the break is pressed

Using equation of motion

v² = u² + 2 a s

0² = 20² - 2 x 10 x s

s = 20 m

Total distance travel by the car = 20 + 10 = 30 m

Distance between deer and car = 49-30 = 19 m.

b. Maximum speed a car could have

Distance travel by the car in reaction time = v' x 0.5

v' is the maximum speed of the car.

maximum distance car can cover = 49 - 0.5 v'

Now, Using equation of motion

v² = u² + 2 a s

0² =v'² - 2 x 10 x (49- 0.5 x v')

v'² +10 v' -980 = 0

By solving

v = 26.7 m/s

Hence, maximum speed of the car can be 26.7 m/s

4 0

4 years ago

Galileo proved the superiority of the heliocentric theory over the geocentric theory, but given our knowledge of the universe to

Naddika [18.5K]

Answer:

Explanation:

Galileo proved the superiority of the heliocentric theory over the geocentric theory . Heliocentric theory changed the centre of universe from the earth to the sun . According to this theory , the solar system or the universe revolves around the sun .

But the present knowledge of universe considers sun as one of billions of stars present in the universe , with each star behaving as sun with its own solar system . The universe is made of cluster of stars with each cluster having their own centre around with they revolve . These clusters are called galaxy . Sun is a part of cluster called milky way . Sun along with other star of this galaxy revolves around the centre of its galaxy which is a super massive star .

Hence the old heliocentric theory does not fit into the present framework of universe by the scientist.

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3 years ago

A child’s toy sits on the bottom of a swimming pool in which the water depth is d=1.8 m. To a child standing at the pool edge, t

navik [9.2K]

Answer:

Horizontal distance is 1.28 + 2.04 = 3.32 m

Explanation:

Given data:

from below figure

Applying Pythagoras theorem

from Snell's law

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$1.33 =\frac{ \frac{2.04}{\sqrt{(3.5 -1.8)^2 + 2.04^2}}}{\frac{x}{\sqrt{1.8^2 + x^2}}}$

solving for x we have

$x^2 = 1.626$

x = 1.28

Horizontal distance is 1.28 + 2.04 = 3.32 m

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3 years ago

50 POINTS! A Boy throws a ball horizontally a distance of 22m downrange from the top of a tower that is 20.0m tall. What is his

DerKrebs [107]

The ball's horizontal and vertical velocities at time $t$ are

$v_x=v_{xi}$

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but the ball is thrown horizontally, so $v_{yi}=0$ . Its horizontal and vertical positions at time $t$ are

$x=v_{xi}t$

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The ball travels 22 m horizontally from where it was thrown, so

$22\,\mathrm m=v_{xi}t$

from which we find the time it takes for the ball to land on the ground is

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3 years ago