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deff fn [24]
3 years ago
11

A thermostat is used for which of the following? maintaining the temperature in a room turning a heating system on turning a hea

ting system off all of the above
Physics
2 answers:
Molodets [167]3 years ago
4 0
All of the above, it's a very useful device :P 
Vlada [557]3 years ago
3 0
Thermostat can do all the three.

So answer is D.
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An inventor claims to have invented a heat engine that receives 750kJ of heat from a source at 400K and produces 250kJ of net wo
IRISSAK [1]

Answer:

the claim is not valid or reasonable.

Explanation:

In order to test the claim we will find the maximum and actual efficiencies. maximum efficiency of a heat engine can be found as:

η(max) = 1 - T₁/T₂

where,

η(max) = maximum efficiency = ?

T₁ = Sink Temperature = 300 K

T₂ = Source Temperature = 400 K

Therefore,

η(max) = 1 - 300 K/400 K

η(max) = 0.25 = 25%

Now, we calculate the actual frequency of the engine:

η = W/Q

where,

W = Net Work = 250 KJ

Q = Heat Received = 750 KJ

Therefore,

η = 250 KJ/750 KJ

η = 0.333 = 33.3 %

η > η(max)

The actual efficiency of a heat engine can never be greater than its Carnot efficiency or the maximum efficiency.

<u>Therefore, the claim is not valid or reasonable.</u>

3 0
3 years ago
A 60 kg man jumps down from a 0.8 m table. What is the speed when he
Rom4ik [11]

Answer: Speed = 4 m/s

Explanation:

The parameters given are

Mass M = 60 kg

Height h = 0.8 m

Acceleration due to gravity g= 10 m/s2

Before the man jumps, he will be experiencing potential energy at the top of the table.

P.E = mgh

Substitute all the parameters into the formula

P.E = 60 × 9.8 × 0.8

P.E = 470.4 J

As he jumped from the table and hit the ground, the whole P.E will be converted to kinetic energy according to conservative of energy.

When hitting the ground,

K.E = P.E

Where K.E = 1/2mv^2

Substitute m and 470.4 into the formula

470.4 = 1/2 × 60 × V^2

V^2 = 470.4/30

V^2 = 15.68

V = square root (15.68)

V = 3.959 m/s

Therefore, the speed of the man when hitting the ground is approximately 4 m/s

4 0
3 years ago
What happens if you go through a black hole ?
devlian [24]

Explanation:

The intense gravity of the black hole would pull you apart, separating your bones and muscles.

7 0
3 years ago
Read 2 more answers
Remember to include your data, equation, and work when solving this problem.
andrezito [222]

Answer:

F = 0.00156[N]

Explanation:

We can solve this problem by using Newton's proposed universal gravitation law.

F=G*\frac{m_{1} *m_{2} }{r^{2} } \\

Where:

F = gravitational force between the moon and Ellen; units [Newtos] or [N]

G = universal gravitational constant = 6.67 * 10^-11 [N^2*m^2/(kg^2)]

m1= Ellen's mass [kg]

m2= Moon's mass [kg]

r = distance from the moon to the earth [meters] or [m].

Data:

G = 6.67 * 10^-11 [N^2*m^2/(kg^2)]

m1 = 47 [kg]

m2 = 7.35 * 10^22 [kg]

r = 3.84 * 10^8 [m]

F=6.67*10^{-11} * \frac{47*7.35*10^{22} }{(3.84*10^8)^{2} }\\ F= 0.00156 [N]

This force is very small compare with the force exerted by the earth to Ellen's body. That is the reason that her body does not float away.

6 0
3 years ago
What are some of the useful properties of current electricity?
Elena-2011 [213]

By definition we have to:

The electric current is the flow of electric charge due to the movement (usually of electrons) that a material travels.

Some properties are:

1) Electric conduction: The conductive materials have a large amount of free electrons, therefore, the passage of electricity is possible.

2) The current inside a circuit is directly proportional to the voltage and inversely proportional to the resistance of the circuit. This is what is known as ohm's law:

I =\frac{V}{R}

3) The current can be continuous or alternate.

Alternating current is the electric current in which the magnitude and direction vary cyclically.

The direct current is the flow of electric charges that does not change direction with time.

8 0
3 years ago
Read 2 more answers
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