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4 years ago

Two identical cars are driving in opposite directions at the same speed. Their kinetic energies have _______________.

Physics

1 answer:

Viktor [21]4 years ago

7 0

Answer: The right answer is c.

Explanation:

The kinetic energy is defined as follows:

K = 1/2 mv²

If both cars are identical, this means that they have the same mass.

Also, we are told that the speed is also the same for both cars.

If they are going in opposite directions, their velocities have the same magnitude, but opposite signs.

But even though they have different signs, the square (which is the parameter relevant for kinetic energy calculations), is always positive, as any number, elevated to an even power, is positive.

So, we conclude that both cars have the same kinetic energy, in magnitude and in sign.

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a 5-kg fish swimming at 1 m/s swallows an absent minded 1-kg fish at rest. What is the speed of the large fish immediately afyer

storchak [24]

Answer:

In first case speed of fish will be $\frac{5}{6}$ m/s.

In the second case the speed of fish $\frac{1}{6}$ m/s

Explanation:

Given data :-

Mass of bigger fish ( m₁ ) = 5 kg.

Mass of small fish ( m₂ ) = 1 kg.

Speed of large fish ( v₁ ) = 1 m/s

Mass of bigger fish after eating smaller one = 5 + 1 = 6 kg.

Case - 1

Momentum of bigger fish before eating the smaller fish = m₁* v₁ = 5 * 1 = 5 kg.m/s

Momentum of bigger fish after eating the larger fish = ( m₁ + m₂)*v

v = speed of bigger fish immediately after lunch.

Using the conservation of momentum.

m₁* v₁ = ( m₁ + m₂)*v

5 = 6 * v

v = $\frac{5}{6}$ m/s.

Case -2

Speed of small fish = 4 m/s

Momentum of bigger fish before lunch = 5 kg.m/s

Momentum of smaller fish before lunch = 4*1 = 4 kg.m/s

Net momentum before lunch = 5 - 4 = 1 kg.m/s

Momentum of bigger fish after eating the larger fish = 6 * V

Using the conservation of momentum.

1 = 6 * V

V = $\frac{1}{6}$ m/s.

3 0

3 years ago

Equal forces that do not cause a change in an object's motion

ss7ja [257]

Answer:

Balanced forces.

Explanation:

The three main forces that stop moving objects are friction, gravity and wind resistance. Equal forces acting in opposite directions are called balanced forces. Balanced forces acting on an object will not change the object's motion. When you add equal forces in opposite direction, the net force is zero.

6 0

3 years ago

You have two resistors with the same cross sectional area and resistivity. Resistor A has length L1 and resistor B has length L2

oee [108]

Answer:

Explanation:

Given

Resistor A has length $L_1$

and Resistor B has Length $L_2$

and Resistance is given by

$R=\frac{\rho L}{A}$

Considering $\rho$ and A to be constant thus

$R_2>R_1$ because $L_2>L_1$

(a)When they are connected in series

As the current in series is same and power is $i^2R$

therefore $P_2>P_1$ as R is greater for second resistor

(b)if they are connected in Parallel

In Parallel connection Voltage is same

$P=\frac{V^2}{R}$

resistance of 2 is greater than 1 thus Power delivered by 1 is greater than 2

8 0

3 years ago

Which best describes how geothermal energy is used to make electricity?. . A.. Rocks are split to release energy that drives a s

In-s [12.5K]

Answer is b that is Heat energy from below the ground converts water to steam to drive a steam turbine attached to an electrical generator.. .

6 0

3 years ago

What might you be doing if you measure your heart rate and find that it beats 100 times in a minute?

alisha [4.7K]

Answer:

Rigorous exercise

Explanation:

For your heart rate is been around 100 bpm you should be doing a rigorous exercise . but if ain't doing any rigorous exercise and your heart rate is constantly above 100 bpm you should consult your doctor.

An average heart is between 60 bpm to 100 bpm.

6 0

3 years ago