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aleksklad [387]
3 years ago
10

A cast iron paperweight is in the shape of a half-sphere with a diameter of 8.2cm. The cast iron has a density of 7.3g/cm^3. Wha

t is the mass of the paperweight, in grams?
a. 16860
b.8430
c.1054
d.2107
Physics
1 answer:
Mnenie [13.5K]3 years ago
8 0

Answer: C

1054 g

Explanation:

Given that the object is in the shape of semi sphere with diameter of 8.2cm. And density of 7.3g/cm^3.

From definition of density,

Density = mass/volume

Volume of a half - sphere = 2/3πr^3

Volume = 2/3 × 3.143 × 4.1^3

Volume = 144.35 cm^3

Let make mass the subject of formula

Mass = Density × volume

Mass = 7.3 × 144.35

Mass = 1053.74g

The mass of the paperweight, in grams is 1054

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A boy throws a ball of mass 0.22 kg straight upward with an initial speed of 29 m/s. When the ball returns to the boy, its speed
maksim [4K]

Answer:

The work is -67.76 J

Explanation:

The law of conservation of energy is considered one of one of the fundamental laws of physics and states that the total energy of an isolated system remains constant. except when it is transformed into other types of energy.

This is summed up in the principle that energy can neither be created nor destroyed in the universe, only transformed into other forms of energy.

In this case you must calculate the loss of kinetic energy. This loss is actually the work done against the resistive force in the air. Friction is the only force other than gravity that acts on the ball.

So, the loss of kinetic energy is \frac{1}{2} *m*(vf^{2} -vi^{2} )

You know:

  • mass=m=0.22 kg
  • Initial velocity of the ball: vi= 29 \frac{m}{s}

Final velocity of the ball: vf= 15 \frac{m}{s}

Replacing:

\frac{1}{2} *0.22 kg*(15^{2} -29^{2} )= -67.76 J

Friction work is always negative because friction is always against displacement.

<u><em>The work is -67.76 J</em></u>

5 0
3 years ago
A plane travels 2.5 KM at an angle of 35 degrees to the ground, then changes direction and travels 5.2 km at an angle of 22 degr
Solnce55 [7]

Answer:

7.7 km 26°

Explanation:

The total x component is:

x = 2.5 cos(35°) + 5.2 cos(22°) = 6.87

The total y component is:

y = 2.5 sin(35°) + 5.2 sin(22°) = 3.38

The magnitude is:

d = √(x² + y²)

d = 7.7 km

The direction is:

θ = atan(y/x)

θ = 26°

5 0
3 years ago
help me pass the test please there is a couple of questions in my profile to answer i am leaving this one for you to help ​
kompoz [17]

Answer:

0.5 m/s².

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 0 m/s

Final velocity (v) = 10 m/s

Time (t) = 20 s

Acceleration (a) =?

Acceleration can simply be defined as the rate of change of velocity with time. Mathematically, it is expressed as:

a = (v – u) / t

Where:

a is the acceleration.

v is the final velocity.

u is the initial velocity.

t is the time.

With the above formula, we can obtain the acceleration of the car as follow:

Initial velocity (u) = 0 m/s

Final velocity (v) = 10 m/s

Time (t) = 20 s

Acceleration (a) =?

a = (v – u) / t

a = (10 – 0) / 20

a = 10/20

a = 0.5 m/s²

Therefore, the acceleration of the car is 0.5 m/s².

6 0
2 years ago
During a total lunar eclipse, where is the Moon located?
krok68 [10]

During a total lunar eclipse, the Moon located in the umbra. The answer is letter A. For a total lunar eclipse to occur, the Sun, Earth and Moon must be aligned in a straight line. The Earth’s umbra complete covers the Moon. The earth’s umbra is about 870,000 miles wide.

5 0
3 years ago
Hello :) how to do this qn?
Finger [1]
The answer is B because oil = blockage of air and it pressures the water to be density of 0.90
3 0
3 years ago
Read 2 more answers
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