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Pachacha [2.7K]
3 years ago
14

Pail of WaterSuppose you wish to whirl a pail full of water in a vertical circle at a constant speed without spilling any of its

contents (even at the top of the circle!). If your arm is 0.70 m long (from shoulder to fist) and the distance from the handle to the surface of the water is 15.0 cm, what minimum speed is required?
Physics
1 answer:
Studentka2010 [4]3 years ago
3 0

Answer:

Velocity will be 2.886 m/sec  

Explanation:

We have given arm length = 0.70 m

And distance from the handle to surface = 15 cm =0.15 m

So total distance r = 0.70+0.15 = 0.85

We know that acceleration is given by a=\frac{v^2}{r}

Here acceleration is acceleration due to gravity so a=g

So g=\frac{v^2}{r}

v=\sqrt{rg}=\sqrt{0.85\times 9.8}=2.886m/sec

So velocity will be 2.886 m/sec

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The spherical side mirror on a car is convex and has a radius of curvature of 25 cm. Another car is following, 20 m behind the m
svlad2 [7]

Answer:

(D) 0.99 cm

Explanation:

Given that the radius of curvature of the mirror is 25 cm.

And another car is following which is behind the mirror of 20 m.

u=20m=2000cm

Focal length is half of the radius of curvature and it is negative for convex lens.

Now the mirror formula.

1/v+1/u=1/f

So,

1/v+1/2000=-1/(25/2)\\1/v=-1/2000-1/12.5\\v=-12.422cm

Now

Magnification is,

m=-v/u

So,

m=12.422/2000=0.00621

So, Height of the image

mh=0.00621\times 1.6 m\\mh=0.0099m\\mh=0.99cm

Therefore, the image height is 0.99 cm.

4 0
3 years ago
4 points
zubka84 [21]

(a) 25lx

(b) 11.11lx

<u>Explanation:</u>

Illuminance is inversely proportional to the square of the distance.

So,

I = k\frac{1}{r^2}

where, k is a constant

So,

(a)

If I = 100lx and r₂ = 2r Then,

I_2 = k\frac{1}{(2r)^2}

Dividing both the equation we get

\frac{I_1}{I_2} = \frac{k}{r^2} X\frac{(2r)^2}{k} \\\\\frac{I_1}{I_2} = 4\\\\I_2 = \frac{I_1}{4}\\\\I_2 = \frac{100}{4}  = 25lx

When the distance is doubled then the illumination reduces by one- fourth and becomes 25lx

(b)

If I = 100lx and r₂ = 3r Then,

I_2 = k\frac{1}{(3r)^2}

Dividing equation 1 and 3 we get

\frac{I_1}{I_2} = \frac{k}{r^2} X\frac{(3r)^2}{k} \\\\\frac{I_1}{I_2} = 9\\\\I_2 = \frac{I_1}{9}\\\\I_2 = \frac{100}{9}  = 11.11lx

When the distance is tripled then the illumination reduces by one- ninth and becomes 11.11lx

3 0
3 years ago
Please help quickly,the picture and choices are above.
Setler79 [48]

Answer:

C because it make sens

C the light wave traveled through ice and then through a Dimond.

7 0
2 years ago
Where in the ocean are u likely to find animals that make there own light
muminat
Usually in the deep sea and underwater caves where there is no light
6 0
3 years ago
Read 2 more answers
A 2.00-kg, frictionless block is attached to an ideal spring with force constant 300 N/m. At t = 0 the spring is neither stretch
r-ruslan [8.4K]

Answer:

a) A = 0.98 m

b) Ф = 90°

c) x = -0.98sin(12.25t)

Explanation:

We know the value of the spring constant which is 300 N/m, the innitial apmplitude, that we will call it xo is 0, at t = 0, and the speed is 12 m/s

The expression for the amplitude under these conditions is:

A = √xo² + vx²/w² (1)

To calculate the angular speed w, we use the following expression:

w = √k/m  (2)

Calculating w:

w = √300/2 = 12.25 rad/s

Now, we replace this value into equation 1, along with the other known values and solve for A:

A = √0 + (12)²/(12.25)²

A = 0.98 m

b) In this part, is actually easy, the displacement of x in function of the time is given by:

x = A cos(wt - Ф) (4)

But at t = 0 we have then:

x = xo = A cosФ (5)

Solving for the angle Ф we have:

xo/A = cosФ

Ф = arccos(x0/A)  (6)

Replacing the data in (6):

Ф = arccos(0/0.98)

Ф = 90°

c) Equation (4) is the expression for the simple harmonic motion

x = A cos(wt - Ф)

And if we replace here the value of w and the previous angle, we can write an equation for x in function of t:

x = 0.98 cos (12.25t - 90)

x = 0.98 cos(12.25t - 90)

And we have an trigonometric expression for cos that is:

cos(α - π/2) = -sinα

in this case, α will be the value of w = 12.25 rad/s. and 90° is the same as rewritting as π/2, therefore:

cos(α - π/2) = cos(12.25t - 90)

x = -0.98sin(12.25t)

3 0
3 years ago
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