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3 years ago

8

Why is it beneficial to perform focal point of a convex lens exercises in a dimly-lit room?

1 answer:

lions [1.4K]3 years ago

7 0

Explanation:

It is given that,

The object distance from the lens is 10 cm, u = -10 cm

Image is formed at a distance of 40 cm away from the lens, u = 40 cm

The lens formula is : $\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}$ , v is image distance

$\dfrac{1}{40}-\dfrac{1}{-10}=\dfrac{1}{f}\\\\f=8\ cm$

The focal length is 8 cm

Magnification,

$m=\dfrac{v}{u}\\\\m=\dfrac{40}{-10}\\\\m=-4$

The magnification is negative, it means that the formed image is inverted.

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A(n) ____________ image cannot be projected and forms where light rays appear to originate.

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A virtual image is the answer.

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A 59 kg physics student is riding her 220 kg Harley at 12 m/s when she has a head-on collision with a 2.1 kg pigeon flying the o

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Answer:

Explanation:

Using conservation of momentum

$m_1=59+220=279kg$

$m_2=2.1kg$

$U_1=12m/s$

$U_2=-44m/s$

$m_1U_1+m_2U_2=(m_1+m_2)V\\\\\frac{278\times 12-2.1\times 44}{279+2.1}=V\\\\V=11.58m/s$

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3 years ago

Scientists were studying three different embryos to determine their relationship to humans. The notes about each embryo are show

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Answer:

The awnser is B

Explanation:

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3 years ago

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A common method to measure thermal conductivity of a biomaterial is to insert a long metallic probe axially into the center of a

tia_tia [17]

Answer:

The thermal conductivity of the biomaterial is approximately 1.571 watts per meter-Celsius.

Explanation:

Let suppose that thermal conduction is uniform and one-dimensional, the conduction heat transfer ( $\dot Q$ ), measured in watts, in the hollow cylinder is:

$\dot Q = \frac{2\cdot k\cdot L}{\ln \left(\frac{D_{o}}{D_{i}} \right)}\cdot (T_{i}-T_{o})$

Where:

$k$ - Thermal conductivity, measured in watts per meter-Celsius.

$L$ - Length of the cylinder, measured in meters.

$D_{i}$ - Inner diameter, measured in meters.

$D_{o}$ - Outer diameter, measured in meters.

$T_{i}$ - Temperature at inner surface, measured in Celsius.

$T_{o}$ - Temperature at outer surface, measured in Celsius.

Now we clear the thermal conductivity in the equation:

$k = \frac{\dot Q}{2\cdot L\cdot (T_{i}-T_{o})}\cdot \ln\left(\frac{D_{o}}{D_{i}} \right)$

If we know that $\dot Q = 40.8\,W$ , $L = 0.6\,m$ , $T_{i} = 50\,^{\circ}C$ , $T_{o} = 20\,^{\circ}C$ , $D_{i} = 0.01\,m$ and $D_{o} = 0.04\,m$ , the thermal conductivity of the biomaterial is:

$k = \left[\frac{40.8\,W}{2\cdot (0.6\,m)\cdot (50\,^{\circ}C-20\,^{\circ}C)}\right]\cdot \ln \left(\frac{0.04\,m}{0.01\,m} \right)$

$k \approx 1.571\,\frac{W}{m\cdot ^{\circ}C}$

The thermal conductivity of the biomaterial is approximately 1.571 watts per meter-Celsius.

8 0

3 years ago

a toy propeller fan with a moment of inertia of .034 kg x m^2 has a net torque of .11Nxm applied to it. what angular acceleratio

Harman [31]

Answer:

The angular acceleration is $\alpha = 3.235 \ rad/s ^2$

Explanation:

From the question we are told that

The moment of inertia is $I = 0.034\ kg \cdot m^2$

The net torque is $\tau = 0.11\ N \cdot m$

Generally the net torque is mathematically represented as

$\tau = I * \alpha$

Where $\alpha$ is the angular acceleration so

$\alpha = \frac{\tau }{I}$

substituting values

$\alpha = \frac{0.1 1}{ 0.034}$

$\alpha = 3.235 \ rad/s ^2$

6 0

3 years ago