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3 years ago

How did black holes get their name

1 answer:

4 0

In 1967, John Wheeler invented the name "black hole" for the first time. However, there is no unified naming system for black holes.

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Help !!!! Estimate the number of breaths taken by a person during 44 years?

Lisa [10]

44 x 12. I got the 12 from the total of 12 months in a year.

44 > 40

x
12 > 10
----------
The way my teacher taught me how to estimate is look at the neighbor to 44 and 12. The only time 44 can become 50, is when the neighbor is 5 or up. Same thing for 12. Now, multiply 40 and 10.

40 x 10 = 400.

Therefore, your estimate is 400.

The real answer is 520 breaths.

6 0

3 years ago

What happens to the temperature during an endothermic reaction? ANSWERS; The temperature stays constant. The temperature will de

EleoNora [17]

Answer:

The temperature will decrease (get colder).

Explanation:

Enthalpy changes are heat changes accompanying physical and chemical changes. The enthalpy change is the difference between the sum of the heat contents of products and the sum of heat contents of reactants.

For an endothermic change, heat is absorbed for the reaction.
The surrounding becomes colder at the end of the reaction and so is the reaction itself.
The right choice is that the temperature will decrease.

6 0

3 years ago

A hockey puck has a mass of 0.107 kg and is at rest. A hockey player makes a shot, exerting a constant force of 28.0 N on the pu

gregori [183]

Answer:

The speed does it head toward the goal = 41.87 $\frac{m}{s}$

Explanation:

Mass = 0.107 kg

Initial velocity ( u ) = 0

Force (F) = 28 N

Time = 0.16 sec

From newton's second law, Force = mass × acceleration

⇒ F = m × a

⇒ 28 = 0.107 × a

⇒ a = 261.7 $\frac{m}{s^{2} }$ --------- (1)

This is the value of acceleration.

Final speed of the mass is calculated by the equation V = U + at

⇒ U = 0 because mass in in rest position at start.

⇒ V = a t

Put the values of acceleration and time in above formula we get

⇒ V = 261.7 × 0.16

⇒ V = 41.87 $\frac{m}{s}$

Therefore the speed does it head toward the goal = 41.87 $\frac{m}{s}$

5 0

3 years ago

Example 3 :

kherson [118]

The friction factor and head loss when velocity is 1m/s is 0.289 and 1.80 × 10^8 respectively. Also, the friction factor and head loss when velocity is 3m/s is 0.096 and 5.3 × 10^8 respectively.

<h3>How to determine the friction factor</h3>

Using the formula

μ = viscosity = 0. 06 Pas

d = diameter = 120mm = 0. 12m

V = velocity = 1m/s and 3m/s

ρ = density = 0.9

a. Velocity = 1m/s

friction factor = 0. 52 × $\frac{0. 06}{0. 12* 1* 0. 9}$

friction factor = 0. 52 × $\frac{0. 06}{0. 108}$

friction factor = 0. 52 × 0. 55

friction factor $= 0. 289$

b. When V = 3mls

Friction factor = 0. 52 × $\frac{0. 06}{0. 12 * 3* 0. 9}$

Friction factor = 0. 52 × $\frac{0. 06}{0. 324}$

Friction factor = 0. 52 × 0. 185

Friction factor $= 0.096$

Loss When V = 1m/s

Head loss/ length = friction factor × 1/ 2g × velocity^2/ diameter

Head loss = 0. 289 × $\frac{1}{2*6. 6743 * 10^-11}$ × $\frac{1^2}{0. 120}$ × $\frac{1}{100}$

Head loss = 1. 80 × 10^8

Head loss When V = 3m/s

Head loss = $0. 096$ × $\frac{1}{1. 334 *10^-10}$ × $\frac{3^2}{0. 120}$ × $\frac{1}{100}$

Head loss = 5. 3× 10^8

Thus, the friction factor and head loss when velocity is 1m/s is 0.289 and 1.80 ×10^8 respectively also, the friction factor and head loss when velocity is 3m/s is 0.096 and 5.3 ×10^8 respectively.

Learn more about friction here:

brainly.com/question/24338873

#SPJ1

4 0

1 year ago

Sam and Ella are arguing at the baseball field. Sam says that if he throws a baseball with a greater speed, it will have a great

Elena L [17]

Don’t still need the answers or are u done and is it on edge

4 0

3 years ago

Read 2 more answers