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3 years ago

What is the speed of a bird of mass 8kg which has kinetic energy of 8836J?

Physics

1 answer:

Kay [80]3 years ago

4 0

Answer:

For the bird moving in a straight line, the kinetic energy is one-half the product of the mass and the square of the speed: Ek=12mu2.

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Suppose a 63-kg boy and a 40-kg girl use a massless rope in a tug-of-war on an icy, resistance-free surface. If the acceleration

kvasek [131]

Answer:

a₂ = 1.9 m/s²

Explanation:

Newton's third law or principle of action and reaction :

Force of the boy on the girl = - Force of the girl on the boy

Fbg = - Fgb Formula (1)

Newton's second law

∑F = m*a Formula (2)

∑F : algebraic sum of the forces in Newton (N)

m : mass in kilograms (kg)

a : acceleration in meters over second square (m/s²)

Newton's second law to the girl

m₁ : girl mass

a₁ : acceleration of the girl toward the boy

∑F = m₁*a₁

Fbg= (40kg)*(3 m/s²)

Fbg = 120 N

Newton's second law to the boy

m₂: boy mass

a₂ : acceleration of the boy toward the girl

∑F = m₂*a₂

Fgb = (63)*a₂

120 = (63)*a₂

a₂ = 120 / (63)

a₂ = 1.9 m/s²

3 0

3 years ago

After the collision, car 1 has a final velocity of 6m/s south. What is the final velocity of car2?

dedylja [7]

I’m almost 100 percent sure it’s the first one

4 0

3 years ago

HELP PLEASE!!!!! pulleys, wheels, and axels.

babymother [125]

The answer is C . 500 N

6 0

4 years ago

Read 2 more answers

A hot-water stream at 80 ℃ enters a mixing chamber with a mass flow rate of 0.5 kg/s where it is mixed with a stream of cold wat

rewona [7]

Answer:

$\dot{m_{2}}=0.865 kg/s$

Explanation:

$\dot{m_1}= 0.5kg/s$

from steam tables , at 250 kPa, and at

T₁ = 80⁰C ⇒ h₁ = 335.02 kJ/kg

T₂ = 20⁰C⇒ h₂ = 83.915 kJ/kg

T₃ = 42⁰C ⇒ h₃ = 175.90 kJ/kg

we know

$\dot{m_{in}}=\dot{m_{out}}$

$\dot{m_{1}}+\dot{m_{2}}=\dot{m_{3}}$

according to energy balance equation

$\dot{m_{in}}h_{in}=\dot{m_{out}}h_{out}$

$\dot{m_{1}}h_{1}+\dot{m_{2}}h_{2}=\dot{m_{3}}h_{3}$

$\dot{m_{1}}h_{1}+\dot{m_{2}}h_{2}=(\dot{m_{1}}+\dot{m_{2}})h_{3}\\(0.5\times 335.02)+(\dot{m_{2}}\times 83.915)=(0.5+\dot{m_{2}})175.90\\\dot{m_{2}}=0.865 kg/s$

4 0

4 years ago

A cell supplies current of 0.6A and 0.2A through 1ohms and 4.0ohms resistor respectively. Calculate the internal resistance of t

Vlad [161]

<h2>Answer:</h2>

0.5Ω

<h2>Explanation:</h2>

Since different currents are passing through the resistors, then the resistors are most probably connected in parallel. This also means that the same voltage will pass across them.

Using Ohm's law, the voltage across a resistor in a circuit is given by;

V = I(R + r) -----------(i)

<em>For the 1ohm resistor, the voltage across it is given by;</em>

<em>Where;</em>

I = current passing through the 1 ohm resistor = 0.6A

R = resistance of the 1 ohm resistor = 1Ω

r = internal resistance of the cell = r

Substitute these values into equation (i) as follows;

V = 0.6(1 + r) -------------------(ii)

<em>For the 4.0ohm resistor, the voltage across it is given by;</em>

<em>Where;</em>

I = current passing through the 4.0 ohms resistor = 0.2A

R = resistance of the 4.0 ohms resistor = 4.0Ω

r = internal resistance of the cell = r

Substitute these values into equation (i) as follows;

V = 0.2(4.0 + r) -------------------(iii)

<em>Now solve equations (ii) and (iii) simultaneously;</em>

V = 0.6(1 + r)

V = 0.2(4.0 + r)

Substitute the value of V in equation (ii) into equation (iii). Therefore, we have;

0.6(1 + r) = 0.2(4.0 + r)

<em>Solve for r</em>

0.6 + 0.6r = 0.8 + 0.2r

0.6r - 0.2r = 0.8 - 0.6

0.4r = 0.2

r = $\frac{0.2}{0.4}$

r = 0.5

Therefore, the internal resistance of the cell is 0.5Ω

4 0

3 years ago