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3 months ago

Rohit placed a pencil perpendicular to principal axis in front of a converging

Physics

1 answer:

serg [3.5K]3 months ago

3 0

Response:

45cm

Clarification:

A converging mirror is generally termed a concave mirror. The focal length and the image distance for a concave mirror are both expressed as positive values.

Using the mirror formula to derive the object distance;

$\frac{1}{f} = \frac{1}{u} + \frac{1}{v}$

Where f denotes the focal length, u indicates the object distance, and v represents the image distance.

Given f = 30cm, and v = 2u (The formed image is double the size of the pencil)

Plugging these values into the formula to solve for u yields;

$\frac{1}{30} = \frac{1}{u} + \frac{1}{2u}\\\frac{1}{30} = \frac{2+1}{2u}\\\frac{1}{30} = \frac{3}{2u}\\$

By cross-multiplying, we obtain;

2u = 90

Dividing both sides by 2;

2u/2 = 90/2

u = 45cm

The object's distance from the mirror measures 45cm

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Answer:

a) The frequency is 3.191x10^11.

b) The type of radiation is microwave radiation.

c) The energy of one quantum of this radiation amounts to 1.32x10^-3ev.

Explanation:

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3 months ago

a 75 kg man is standing at rest on ice while holding a 4kg ball. if the man throws the ball at a velocity of 3.50 m/s forward, w

Keith_Richards [3271]

Answer:

The resulting velocity for him will be 0.187 m/s in reverse direction.

Explanation:

Given:

The mass of the man is, $M=75\ kg$

The mass of the ball is, $m=4\ kg$

The initial velocity of the man is, $u_m=0\ m/s(rest)$

The initial velocity of the ball is, $u_b=0\ m/s(rest)$

The final velocity of the ball is, $v_b=3.50\ m/s$

The final velocity of the man is, $v_m=?\ m/s$

To determine this scenario, we employ the principle of momentum conservation.

This principle states that the total initial momentum equals the total final momentum.

Momentum is calculated by multiplying mass by velocity.

Initial momentum = Initial momentum of the man and the ball

Initial momentum = $Mu_m+mu_b=75\times 0+4\times 0 =0\ Nm$

Final momentum = Final momentum of the man and the ball

Final momentum = $Mv_m+mv_b=75\times v_m+4\times 3.50 =75v_m+14$

Hence, the total initial momentum equals the total final momentum

$0=75v_m+14\\\\75v_m=-14\\\\v_m=\frac{-14}{75}\\\\v_m=-0.187\ m/s$

The negative sign indicates that the man moves backward.

Thus, his final velocity ends up being 0.187 m/s backward.

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2 months ago

The spring in a retractable ballpoint pen is 1.8 cm long, with a 300 N/m spring constant. When the pen is retracted, the spring

Sav [3153]

Answer:

The pen requires 7.2 mJ of energy to extend.

Explanation:

Provided:

Length = 1.8 cm

Spring constant = 300 N/m

Initial compression = 1.0 mm

Additional compression = 6.0 mm

Total compression = 1.0 + 6.0 = 7.0 mm

We need to determine the energy needed

This energy is equivalent to the variation in spring potential energy

$E=PE_{2}-PE_{1}$

$E=\dfrac{1}{2}kx_{2}^2-\dfrac{1}{2}kx_{1}^2$

Substitute the values into the formula

$E=\dfrac{1}{2}\times300\times(7.0\times10^{-3})^2-\dfrac{1}{2}\times300\times(1.0\times10^{-3})^2$

$E=0.0072\ J$

$E=7.2\ mJ$

Therefore, a total of 7.2 mJ is needed to extend the pen.

7 0

3 months ago

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