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OLga [1]
2 years ago
11

A power station burns 75 kilograms of coal per second. Each kg of coal contains 27 million joules of energy.

Physics
1 answer:
Kaylis [27]2 years ago
3 0

Answer:

Explanation:

a )

one kg of coal gives energy of 27 x 10⁶ J

75 kg of coal gives energy of 27 x 10⁶ x 75 J

So rate which energy is coming out of coal per second

= 27 x 10⁶ x 75 J

= 2025 x 10⁶ J /s

2025 million watts .

b ) energy output = 800 million watts

efficiency = (800 / 2025) x 100

= 39.5 % .

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Did the kinetic frictional coefficient (for the wood/aluminum and felt/aluminum cases) vary with area of contact
lawyer [7]

Answer:

Explanation:

Friction is defined as a force which acts at the surface of separation between two objects in contact and tends to oppose motion of one over the other.

While kinetic friction is the force that must be overcome so that a body can move with uniform speed over another.

Hence let consider one of the laws of friction which states that: '' Frictional force is independent of the area of the surfaces in contact.''

The value did not vary with area. This is because when calculating the kinetic fiction, the total contact area is not relevant and only the total weight of the system as well of as the block is put into consideration.

5 0
1 year ago
Consider as a system the gas in a vertical cylinder; the cylinder is fitted with a piston on which a number of small weights are
Amiraneli [1.4K]

Answer:

Explanation:

a ) At constant pressure , work done = P x Δ V

= 200 x 10³ x ( .1 - .04 )

= 12 x 10³ J .

b )

At constant temperature work done

= n RT ln v₂ / v₁

= PV ln v₂ / v₁

= 200 x 10³ x .04 ln .1 / .04

8 x 10³ x .916

= 7.33 x 10³ J .

5 0
1 year ago
Vectors a and b have scalar product â6.00, and their vector product has magnitude +9.00. what is the angle between these two vec
salantis [7]

Answer:

Value of angle between vector a and b is 56.30^{\circ}.

Explanation:

Vectors a and b have scalar product 6.00

Let \theta be the angle between a and b.

\vec{a}.\vec{b} = 6

ab cos \theta = 6 ...(1)

Vectors a and b have magnitude of vector product 9.00

\vec{a} \times\vec{b} = 9

ab sin \theta = 9 ...(2)

Dividing equation (2) by (1) we get

\frac{ab sin \theta}{ab cos \theta}  = \frac{9}{6}

tan \theta = 1.5

\theta = tan ^{-1} (1.5)

\theta = 56.30^{\circ}

Thus, value of angle between vector a and b is 56.30^{\circ}.

3 0
2 years ago
A spaceship is travelling at 20,000.0 m/s. After 5.0 seconds, the rocket thrusters are turned on. At the 55.0 second mark, the s
tankabanditka [31]

Answer:

80 m/s^2

Explanation:

The acceleration of an object is given by:

a=\frac{v-u}{t}

where

v is the final velocity

u is the initial velocity

t is the time interval it takes for the velocity to change from u to v

For the rocket in this problem,

u = 20,000 m/s

v = 24,000 m/s

t = 55.0 - 5.0 = 50.0 s

Substituting,

a=\frac{24000-20000}{50}=80 m/s^2

7 0
2 years ago
A race car has a maximum speed of 0.104 km/s .What is this speed in miles per hour ?
sweet [91]

Answer:

232.641374 mph

Explanation:

A race car has a maximum speed of 0.104km/s

Let X represent the speed in miles per hour

Therefore the speed in miles per hour can be calculated as follows

1 km/s = 2,236.936292 mph

0.104km/s = X

X = 0.104 × 2,236.936292

X = 232.641374

Hence the speed in miles per hour is 232.641374 mph

8 0
2 years ago
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