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3 years ago

In which situation is no work considered to be done by a force?

1 answer:

8 0

If the angle is either 0 or 180, that means that there is either negative or positive work, so A and D are not correct.
If the angle is 45, then there is still some work involved.
The only option where there is no work done by a force is B. when the angle is between the force and displacement is 90.

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A screen is placed a distance dd to the right of an object. A converging lens with focal length ff is placed between the object

Elina [12.6K]

Answer:

Explanation:

The formula for the object - image relationship of thin lens is given as;

1/s + 1/s' = 1/f

Where;

s is object distance from lens

s' is the image distance from the lens

f is the focal length of the lens

Total distance of the object and image from the lens is given as;

d = s + s'

We earlier said that; 1/s + 1/s' = 1/f

Making s' the subject, we have;

s' = sf/(s - f)

Since d = s + s'

Thus;

d = s + (sf/(s - f))

Expanding this, we have;

d = s²/(s - f)

The derivative of this with respect to d gives;

d(d(s))/ds = (2s/(s - f)) - s²/(s - f)²

Equating to zero, we have;

(2s/(s - f)) - s²/(s - f)² = 0

(2s/(s - f)) = s²/(s - f)²

Thus;

2s = s²/(s - f)

s² = 2s(s - f)

s² = 2s² - 2sf

2s² - s² = 2sf

s² = 2sf

s = 2f

8 0

3 years ago

(a) Calculate the self-inductance (in mH) of a 55.0 cm long, 10.0 cm diameter solenoid having 1000 loops.

DedPeter [7]

Explanation:

(a) We have,

Length of solenoid, l = 55 cm = 0.55 m

Diameter of the solenoid, d = 10 cm

Radius, r = 5 cm = 0.05 m

Number of loops in the solenoid is 1000.

(a) The self inductance in the solenoid is given by :

$L=\dfrac{\mu_o N^2A}{l}$

A is area

$L=\dfrac{4\pi \times 10^{-7}\times (1000)^2\times \pi (0.05)^2}{0.55}\\\\L=0.0179\ H\\\\L=17.9\ mH$

(b) The energy stored in the inductor is given by :

$E=\dfrac{1}{2}LI^2\\\\E=\dfrac{1}{2}\times 0.0179\times (19.5)^2\\\\E=3.4\ J$

Hence, this is the required solution.

4 0

2 years ago

Kepler's first law states that planets orbit the Sun in a path called a(n)

wariber [46]

The answer would be C.

3 0

3 years ago

Read 2 more answers

The brakes application to a car produce an acceleration of 6ms2 in the opposite direction to the motion .If the car takes 2 seco

Anna [14]

Answer:12 meter

Explanation:

acceleration(a)=6m/s^2

Time(t)=2 seconds

Distance =(a x t^2)/2

Distance =(6 x 2^2)/2

Distance=(6 x 2 x 2)/2

Distance=24/2

Distance =12

Distance is 12 meters

7 0

2 years ago

Group 18 noble gases are inert because

hammer [34]

Answer:

Explanation:

have a full 8 electrons on the outermost ring

4 0

3 years ago