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zmey [24]
3 years ago
5

ALWAYS use significant figure rules. Remember that these rules apply to all numbers that are measurements.

Physics
1 answer:
natali 33 [55]3 years ago
8 0

Answer:

Well I'm going to go with A.

Explanation:

As per the question the mass of the boy is 40 kg.

The boy sits on a chair.

We are asked to calculate the force exerted by the boy on the chair at sea level.

The force exerted by boy on the chair while sitting on it is nothing else except the force of gravity of earth i.e the weight of the body .The direction of that force is vertically downward.

At sea level the acceleration due to gravity g = 9.8 m/s^2

Therefore, the weight of the boy  [m is the mass of the body]

we have m = 40 kg.

                             Therefore, w = 40 kg ×9.8 m/s^2

                                             =392 N kg m/s^2

                                              = 392 N

392 is not an option but I'm guessing you can round down 2 .to option A. 390...?

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Use the circuit diagram to decide if the lightbulb will light. Justify your answer.
podryga [215]

Answer:

The lightbulb will NOT light.

Explanation:

You put me in a difficult position.  I can't help it, but the "sample answer" is by far the best way to explain this, briefly and correctly.  There's no other choice but to copy it.

This is a short circuit. The branch without the bulb has almost no resistance, so all the current will flow through that branch instead of flowing through the bulb.

<em>If</em> the lower switch were <u>opened</u>, THEN we would have a series circuit.  Current would no longer have any other choice but to flow through the bulb, and the bulb would light.

5 0
3 years ago
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Who makes the first atomic bomb?​
Svetradugi [14.3K]

Answer:

Robert Oppenheimer made the first atomic bomb.

7 0
3 years ago
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An automobile tire having a temperature of
EastWind [94]

Answer:

Psm = 30.66 [Psig]

Explanation:

To solve this problem we will use the ideal gas equation, recall that the ideal gas state equation is always worked with absolute values.

P * v = R * T

where:

P = pressure [Pa]

v = specific volume [m^3/kg]

R = gas constant for air = 0.287 [kJ/kg*K]

T = temperature [K]

<u>For the initial state</u>

<u />

P1 = 24 [Psi] + 14.7 = 165.47[kPa] + 101.325 = 266.8 [kPa] (absolute pressure)

T1 = -2.6 [°C] = - 2.6 + 273 = 270.4 [K] (absolute Temperature)

Therefore we can calculate the specific volume:

v1 = R*T1 / P1

v1 = (0.287 * 270.4) / 266.8

v1 = 0.29 [m^3/kg]

As there are no leaks, the mass and volume are conserved, so the volume in the initial state is equal to the volume in the final state.

V2 = 0.29 [m^3/kg], with this volume and the new temperature, we can calculate the new pressure.

T2 = 43 + 273 = 316 [K]

P2 = R*T2 / V2

P2 = (0.287 * 316) / 0.29

P2 = 312.73 [kPa]

Now calculating the manometric pressure

Psm = 312.73 -101.325 = 211.4 [kPa]

And converting this value to Psig

Psm = 30.66 [Psig]

3 0
3 years ago
When hydrogen is burned in the presence of oxygen it will form water as per the equation: 2h2
Natasha_Volkova [10]

Answer:

B. In the first case, a combination reaction takes place and in the second case, a decomposition reaction takes place.

Explanation:

When hydrogen burns in oxygen, water is formed and when water is electrolysed then hydrogen and oxygen are produced. What type of a reaction takes place?

(i) In the first case,

(ii) In the second case?

A. In both the cases, i.e. (i) and (ii), a combination reaction takes place.

B. In the first case, a combination reaction takes place and in the second case, a decomposition reaction takes place.

C. In the first case, a combination reaction takes place and in the second case, a displacement reaction takes place.

D. In the first case, a displacement reaction takes place and in the second case, a decomposition reaction takes place.

Answer :

Hint: When hydrogen burns in air, H2H2 reacts with O2O2 to form water molecules. Here two reactants combine to form a single product. And, when water is electrolysed into hydrogen and oxygen, here a single compound decomposes into more than one product.

Complete step by step answer:

In the First case:

When hydrogen burns in oxygen, water is formed.

Hydrogen + Oxygen = Water

2H2+O2→2H2O2H2+O2→2H2O

When two reactants elements combine to form a single component, then this reaction is called the combination reaction. So, in this case, two reactants i.e. Hydrogen and oxygen combine to form a single product i.e. water molecules and heat is also released.

In the Second case:

When water is electrolysed then hydrogen and oxygen are produced.

2H2O→2H2+O22H2O→2H2+O2

When a single reactant is decomposed or broken down into two or more products, it is known as decomposition reaction. Here, a single reactant i.e. water, breaks or decomposes up to form two or more simple products i.e. hydrogen and oxygen. This decomposition reaction takes place by the action of electricity. So, we can see that in the first case, a combination reaction takes place and in the second case, a decomposition reaction takes place.

Therefore, the correct answer is option (B).

Note: Hydrogen is combustible and it burns with a popping sound in oxygen with an almost colourless flame to form water molecules and release heat. This reaction is highly exothermic. Hydrogen must be handled very carefully as the mixture of hydrogen and oxygen can be explosive when two are present in a particular ratio.

7 0
2 years ago
A force of 60 N is applied to a skier to pull him along a horizontal surface so that his speed remains constant. If the coeffici
matrenka [14]

Answer:

1200\ \text{N}

Explanation:

F = Force on the skier = 60 N

\mu = Coefficient of friction = 0.05

w = Weight of skier

Force is given by

F=\mu w

\Rightarrow w=\dfrac{F}{\mu}

\Rightarrow w=\dfrac{60}{0.05}=\dfrac{6000}{5}

\Rightarrow w=1200\ \text{N}

Weight of the skier on which the force is being applied is 1200\ \text{N} .

7 0
3 years ago
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