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4 years ago

6

A uniform ladder of length l rests against a smooth, vertical wall. If the mass of the ladder is m and the coefficient of static

friction between the ladder and the ground is 0.40, find the minimum angle at which the ladder does not slip.
What If? What if a person begins to climb the ladder when the angle is 51°? Will the presence of a person on the ladder make it more or less likely to slip?

1 answer:

Alex Ar [27]4 years ago

4 0

Answer:

51.3 Degrees

The presence of person above the center of mass of ladder will make the ladder more likely to slip.

Explanation:

Explanation in the attachment.

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A stone is dropped from the

ICE Princess25 [194]

Height=h=500m
Acceleration=g=10m/s^2
Initial velocity=u=0
Speed of sound=c=340m/s
TIME TAKEN BY STONE TO HIT WATER=t
Time taken by sound to hear back=T

Now

$\\ \sf\longmapsto h=ut+\dfrac{1}{2}gt^2$

$\\ \sf\longmapsto h=0t+\dfrac{1}{2}10t^2$

$\\ \sf\longmapsto 500=5t^2$

$\\ \sf\longmapsto t^2=100$

$\\ \sf\longmapsto t=10s$

Now

$\\ \sf\longmapsto h=cT$

$\\ \sf\longmapsto T=\dfrac{h}{c}$

$\\ \sf\longmapsto T=\dfrac{500}{340}$

$\\ \sf\longmapsto T=1.47\approx 1.5s$

Total time:-

$\\ \sf\longmapsto T_{net}=t+T=10+1.5=11.5s$

8 0

2 years ago

What is the frictional force between a box and the floor it is being pulled across if, the kinetic coefficient of friction is 0.

Artyom0805 [142]

If the pulling is done parallel to the floor with constant velocity, then the box is in equilibrium. In particular, the weight and normal force cancel, so that

<em>n</em> = 38 N

The friction force is proportional to the normal force by a factor of 0.27, so that

<em>f</em> = 0.27 (38 N) ≈ 10.3 N

and so the answer is D.

8 0

3 years ago

Lucille is finding it difficult to play soccer after school. Her doctor thinks that her cells might not be getting enough oxygen

lana66690 [7]

Answer:

See the explanation below.

Explanation:

Circulation of blood and oxygen is possible in body when circulatory system work along with respiratory system. Through tranche air moves in and out from lungs, whereas, through pulmonary arteries and veins (both connected to heart) blood moves in and out from the lungs. As Lucille is facing problem in his respiratory and circulatory system hence, it is difficult for him to play soccer because under normal circumstances when there is increase in physical activity then muscle cell respire more as compare to when the body is on rest. So, with increase of physical activity there is also increase in the rate of breathing which result in more absorption of oxygen and more removal of carbon dioxide but if there is problem in respiratory and circulatory system, for example, infection in throat due to pollution,etc. then this normal process of breathing gets affected which sometime may prove fatal to the person.

4 0

3 years ago

If you could shine a very powerful flashlight beam toward the Moon, estimate the diameter of the beam when it reaches the Moon.

grin007 [14]

To develop this problem it is necessary to apply the Rayleigh Criterion (Angular resolution)criterion. This conceptos describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution. By definition is defined as:

$\theta = 1.22\frac{\lambda}{d}$

Where,

$\lambda$ = Wavelength

d = Width of the slit

$\theta$ = Angular resolution

Through the arc length we can find the radius, which would be given according to the length and angle previously described.

The radius of the beam on the moon is

$r = l\theta$

Relacing $\theta$

$r = l(\frac{1.22\lambda}{d})$

$r = 1.22\frac{l\lambda}{d}$

Replacing with our values we have that,

$r = 1.22*(\frac{(384*10^3km)(\frac{1000m}{1km})(550*10^{-9}m)}{7*10^{{-2}}})$

$r = 3680.91m$

Therefore the diameter of the beam on the moon is

$d = 2r$

$d = 2 * (3690.91)$

$d = 7361.8285m$

Hence, the diameter of the beam when it reaches the moon is 7361.82m

8 0

4 years ago

Melissa's favorite exercise equipment at the gym consists of various springs. in one exercise, she pulls a handle grip attached

konstantin123 [22]

The formula for force exerted on/by a spring is

F = k*e where k is the spring constant and x is the distance stretched from unstrained position. This should allow you to find what you need.

Using F = k x e,

where k is the spring constant,

and e is the extension,

The F is her weight = 45 X 0.80

= 36 N

6 0

3 years ago