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3 years ago

10

Which material is a composite? A. gold B.silicon C.polycarbonate D.aluminum

1 answer:

sweet [91]3 years ago

6 0

Answer:

I think gold

Explanation:

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What minimum heat is needed to bring 250 g of water at 20 ∘C to the boiling point and completely boil it away? The specific heat

Amiraneli [1.4K]

Answer:633.8 KJ

Explanation:

Given

mass of water $\left ( m\right )=250gm$

Initial temperature $\left ( T_i\right )=20^{\circ}C$

Final temperature $\left ( T_f\right )=100^{\circ}C$

Specific heat of water $\left ( c \right )$ =4190 J/kg-k

heat of vaporization $\left ( L\right )=22.6\times 10^5 J/kg$

Heat required for process $\left ( Q\right )$ =heat to raise water temperature from 20 to 100 +Heat to vapourize water completely

Q=mc $\left ( T_f-T_i\right )+mL$

Q= $0.25\times 4190\times \left ( 100-20\right )+0.25\times 22\times 10^5$

Q= $\left ( 0.838+5.5\right )\times 10^5$

Q= $6.338\times 10^5J=633.8 KJ$

4 0

4 years ago

A force of 40 N is applied in a direction perpendicular to the end of a 9 m long bar that pivots about its other end. Find the t

snow_lady [41]

Answer:

360 Nm

Explanation:

Torque: This is the force that tend to cause a body to rotate or twist. The S.I unit of torque is Newton- meter (Nm).

From the question,

The expression of torque is given as

τ = F×d......................... Equation 1

Where, τ = Torque, F = force, d = distance of the bar perpendicular to the force.

Given: F = 40 N, d = 9 m

Substitute into equation 1

τ = 40(9)

τ = 360 Nm.

5 0

4 years ago

Read 2 more answers

Scientists want to place a 3400.0 kg satellite in orbit around Mars. They plan to have the satellite orbit at a speed of 2480.0

BaLLatris [955]

Answer:

Part a)

$r = 6.96 \times 10^6 m$

Part b)

$F_g = 3.004 \times 10^3 N$

Part c)

$a = 0.88 m/s^2$

Part d)

$v = \frac{2480}{2} = 1240 m/s$

Explanation:

Part a)

As we know that the orbital speed of the satellite is given as

$v = 2480 m/s$

now we will have

$v = \sqrt{\frac{GM_{mars}}{r}}$

now we have

$M_{mars} = 6.4191 \times 10^{23} kg$

$R_{mars} = 3.397 \times 10^6 m$

now we have

$2480 = \sqrt{\frac{(6.67 \times 10^{-11})(6.4191 \times 10^{23})}{r}}$

$r = 6.96 \times 10^6 m$

Part b)

Here force between mars and satellite is the gravitational attraction force which is given as

$F_g = \frac{GM_{mars} m}{r^2}$

$F_g = \frac{(6.67\times 10^{-11})(6.4191 \times 10^{23})(3400)}{(6.96\times 10^6)^2}$

$F_g = 3.004 \times 10^3 N$

Part c)

Acceleration of satellite is the ratio of gravitational force and mass of the satellite

$a = \frac{F_g}{m}$

$a = \frac{3004}{3400}$

$a = 0.88 m/s^2$

Part d)

As we know by III law of kepler

$\frac{T_1^2}{T_2^2} = \frac{r_1^3}{r_2^3}$

here we know that T2 = 8 T1

$(\frac{1}{8})^2= \frac{r_1^3}{r_2^3}$

$\frac{r_1}{r_2} = (\frac{1}{2})^2$

so we have

$r_2 = 4r_1$

as we know that speed is given as

$v = \sqrt{\frac{GM}{r}}$

so we can say since radius is orbit becomes 4 times so the orbital speed must be half

$v = \frac{2480}{2} = 1240 m/s$

7 0

4 years ago

What is a definition for reactivity with vinegar?

STALIN [3.7K]

The answer to this is Chemical property.

6 0

3 years ago

Name and define the SI unit of magnetic field?

kozerog [31]

Answer:

The tesla is the SI unit for the magnetic field (T). One tesla is the magnetic field in which a charge of one coulomb travelling perpendicular to the magnetic field at a velocity of 1 m/s receives a force of one newton.

<u>OAmalOHopeO</u>

3 0

3 years ago