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Keith_Richards [23]
3 years ago
13

A train travels 99 kilometers in 2 hours, and then 90 kilometers in 3 hours. What is its average speed?

Physics
1 answer:
Agata [3.3K]3 years ago
3 0

Average speed =

(total distance)/(total time)

Average speed = (99+90)/(2+3)

That's (189 km) / (5 hr)

Average speed = 37.8 km/hr

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Both a 3 kg book and 5 kg bowling ball are sitting still on the floor. What is true about the kinetic energy of the objects? Exp
Charra [1.4K]

Answer:

The kinetic energy for both objects is the same.

Explanation:

While in other cases the kinetic energies of two objects that have different masses might be different depending on their velocities, in this case both the 3 kg book and 5 kg bowling ball have the same kinetic energy.

This is because kinetic energy is calculated using the formula: K = 1/2 * m * v^2, where m represents the mass and v represents the velocity of the object.

Since the book and the bowling ball are sitting still on the floor, their velocities are zero.  Hence, when we plug in 0 for velocity into the equation for kinetic energy, we will get that the kinetic energy is 0 for the book and the bowling ball.

Hope this helps!

6 0
3 years ago
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
lorasvet [3.4K]

\large{\underline{\underline{\pmb{\frak {\color {red}{Question:}}}}}}

\sf \red{When \: baking \: soda \: is \: mixed \: with \: lemon \: juice, \: bubbles \: are \: formed \: with \: the \: evolution \: of \: a \: gas.}

\large{\underline{\underline{\pmb{\frak {\color {blue}{Answer:}}}}}}

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. The gas is formed in the reaction is Carbon dioxide. CO_{2} is formed.

The change which happened in this reaction is a chemical change.

\boxed{ \frak \green{Explanation}}

Since, in chemical change we can't bring a substance to it's actual form how it was in earlier.

Examples: burning of paper is chemical, since we can't get the fine paper again after it is burnt.

Thus, the above reaction is also a chemical change, since we can't get back the lemon juice how it was earlier.

\boxed{ \frak \red{Brainlysamurai}}

5 0
2 years ago
There is a current of 0.83 A through a lightbulb in a 120 V circuit. What is the resistance of this lightbulb?
Lemur [1.5K]

Considering the Ohm's law, the resistance of the lightbulb is 144.58 Ω.

<h3>Definition of current</h3>

The flow of electricity through an object, such as a wire, is known as current (I). Its unit of measure is amps (A). So the current is a measure of the speed at which the charge passes a given reference point in a specified direction.

<h3>Definition of voltage</h3>

The driving force (electrical pressure) behind the flow of a current is known as voltage and is measured in volts (V) (voltage can also be referred to as the potential difference or electromotive force). That is, voltage is a measure of the work required to move a charge from one point to another.

<h3>Definition of resistance</h3>

Resistance (R) is the difficulty that a circuit opposes to the flow of a current and it is measured in ohms (Ω).

<h3>Ohm's law</h3>

Ohm's law establishes the relationship between current, voltage, and resistance in an electrical circuit.

This law establishes that the intensity of the current that passes through a circuit is directly proportional to the voltage of the same and inversely proportional to the resistance that it presents.

Mathematically, Ohm's law is expressed as:

I=\frac{V}{R}

Where:

  • I is the current measured in amps (A).
  • V the voltage measured in volts (V).
  • R the resistance that is measured in ohms (Ω).

<h3>Resistance of the lightbulb</h3>

In this case, you know that the voltage between two points in a circuit is 120 V and there is a current of 0.83 A.

Replacing in the Ohm's Law:

0.83A=\frac{120 V}{R}

Solving:

0.83 A× R=  120 V

R=\frac{120 V}{0.83A}

<u><em>R= 144.58 Ω</em></u>

Finally, the resistance of the lightbulb is 144.58 Ω.

Learn more about Ohm's law:

brainly.com/question/13076023

brainly.com/question/17286882

brainly.com/question/2275770

#SPJ1

3 0
2 years ago
En el mar, la luz visible alcanza una profundidad de aproximadamente 200 metros (zona fotica). ¿De dónde obtienen energías las p
Marizza181 [45]

Answer:

Explanation:

En la zona apótica (profundidad inferior a 200 m); todo lo que queda de la luz solar es una luz tenue, opaca, azul-verde, demasiado impotente para siquiera considerar permitir que ocurra la fotosíntesis. Sin embargo, hay comida para tener; basura, trozos de plantas podridas y derroche de criaturas caen desde arriba para cuidar a los seres vivos en la zona apótica.

Las formas de vida a una profundidad inferior a 200 m dependen de los productos químicos que salen de los respiraderos; el procedimiento que utilizan para hacer los alimentos se llama quimiosíntesis en lugar de fotosíntesis.

3 0
3 years ago
When a wave is acted upon by an external damping force what happens to the energy of the wave
Nimfa-mama [501]

Answer:

A-the energy of the wave decreases gradually

Explanation:

when a wave is acted upon by an external damping force the energy of the wave decreases gradually.

The energy degrades into the form of heat which is considered to be of less value and use. The reason is because it disperses and spreads more widely.

So therefore it end up as heat with a little sound but that is close to none because that too disperses into heat i.e. decreased form of energy.

4 0
3 years ago
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