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3 years ago

What is the second law of thermodynamics

Physics

1 answer:

andriy [413]3 years ago

5 0

It states that the total entropy of an isolated system can never decrease over time

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Which statement describes absolute and apparent brightness?

xeze [42]

The answer is: Absolute brightness is the actual amount of light produced by the star, whereas apparent brightness changes with distance from the observer. Hope this helps, and have a great day

7 0

3 years ago

Read 2 more answers

A gazelle leaps from a cliff 2.5 m high with a speed of 5.6m/s.

trapecia [35]

Initial speed of Gazelle is along x direction and its value will be

$v_x = 5.6 m/s$

also its initial height is given as

$y = 2.5 m$

Part a)

now from kinematics along Y direction

$\Delta y = v_y t + \frac{1}{2} at^2$

as we know that

$\Delta y = 0$

$v_y = 0$

$a = 9.8 m/s^2$

$2.5 = 0 + \frac{1}{2} (9.8) t^2$

$t = 0.714 s$

Part b)

distance moved horizontally

$\Delta x = v_x t$

as we know that

$v_x = 5.6 m/s$

now we will have

$v_x = 5.6 (0.714) = 4m$

so it will lend at distance of 4 m.

Part c)

final velocity in vertical direction

$v_{fy} = v_y + at$

$v_{fy} = 0 + (9.8)(0.714) = 7 m/s$

$v_x = 5.6 m/s$

so net speed will be

$v^2 = v_x^2 + v_y^2$

$v^2 = 7^2 + 5.6^2$

$v = 8.96 m/s$

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4 years ago

Serving at a speed of 164 km/h, a tennis player hits the ball at a height of 2.23 m and an angle θ below the horizontal. The ser

sweet-ann [11.9K]

Answer:

The angle θ is 6.1° below the horizontal.

Explanation:

Please, see the figure for a description of the situation.

The vector "r" gives the position of the ball and can be expressed as the sum of the vectors rx + ry (see figure).

We know the magnitude of these vectors:

magnitude rx = 11.6 m

magnitude ry = 2.23 m - 0.99 m = 1.24 m

Then:

rx = (11. 6 m, 0)

ry = (0, -1.24 m)

r = (11.6 m + 0 m, 0 m - 1.24 m) = (11.6 m, -1.24 m)

Using trigonometry of right triangles:

magnitude rx = r * cos θ = 11. 6 m

magnitude ry = r * sin θ = 2.23 m - 0.99 = 1.24 m

where r is the magnitude of the vector r

magnitude of vector r:

$r = \sqrt{(11.6m)^{2} + (1.24m)^{2}} = 11.667m$

Then:

cos θ = 11.6 m / 11.667 m

θ = 6.1°

Using ry, we should obtain the same value of θ:

sin θ = 1.24 m/ 11.667 m

θ = 6.1°

( the exact value is obtained if we do not round the module of r)

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3 years ago

A boat floats in a lake. When the boat moves the force of resistance is proportional to the velocity of the boat. Initially the

m_a_m_a [10]

Answer: Contant.

Explanation:

You are given that When the boat moves the force of resistance is proportional to the velocity of the boat. This means that the total momentum on the boat is equal to zero. Then the boat remains at a certain position.

When a person walks from the stern to the bow of the boat, the boat will tend to move in the opposite direction with equal magnitude of momentum. The magnitude of forces will thereby cancel out.

The person will be seen moving while the boat moves in the opposite direction.

If no external force is acting on the boat, the sum of the momentum of the person and the boat will be equal to zero. And the boat will remain at rest.

The position of the boat long time after the person stopped moving will therefore remain the same.

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3 years ago

If a 50kg boulder is 100m off the ground and a 25 kg boulder is 100 m off the ground, which has a

Flauer [41]

Answer:

Explanation:

It 100 kg It think

6 0

3 years ago