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slamgirl [31]
3 years ago
6

Estimate how long it would take one person to mow a football field using an ordinary home lawn mower. Assume the mower moves wit

h a 1 km/h speed, and has a 0.6 m width
Physics
1 answer:
bekas [8.4K]3 years ago
8 0

Answer:

t = 11.9 h = 0.49 day

Explanation:

First of all, we will find the area covered by the mower per unit time:

Rate\ of\ Area\ Covered\ by\ Mower = vw

where,

v = speed of mower = 1 km/h = 1000 m/h

w = width of mower = 0.6 m

Therefore,

Rate\ of\ Area\ Covered\ by\ Mower = (1000\ m/h)(0.6\ m)\\Rate\ of\ Area\ Covered\ by\ Mower = 600\ m^{2}/h

Now, the standard football ground has an area of:

A = 105 m x 68 m = 7140 m²

Therefore, The time required to mow the lawn will be:

Time\ to\ Mow\ the\ Lawn = t = \frac{A}{Rate\ of\ Area\ Covered\ by\ Mower}\\t = \frac{7140\ m^{2}}{600\ m^{2}/h}

<u>t = 11.9 h = 0.49 day</u>

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A horse was at rest.what was the final velocity of the horse if it covered 200 meters in 16 seconds?
skelet666 [1.2K]

Answer:

<u>12.5m/s</u>

Explanation:

Simplify the proportion.

200/16 = 100/8 = 50/4 = 25/2 = <u>12.5</u>

5 0
3 years ago
Confining pressure is where ________. Confining pressure is where ________. pressure is parallel to the bedding planes pressure
Brrunno [24]

Answer:

d) Forces are applied equally in all directions

Explanation:

Confining pressures are pressures imposed on a layer of soil by the weights of the layers on top of it. Confining pressures occur as a result of equal transmission of forces between the layers of a material (usually rock and soil).

It can also be described as an equal, all-sided pressure produced by overlying rocks in the crust of the earth.  As the confining pressure increases, the critical elastic energy of the layers of the material transforms from linear to exponential.

5 0
3 years ago
A fan is to accelerate quiescent air to a velocity of 8 m/s at a rate of 9 m3 /s. determine the minimum power that must be suppl
ELEN [110]
Given:
ρ = 1.18 kg/m³, density of air
v = 8 m/s, flow velocity
Q = 9 m³/s, volumetric flow rate

The minimum power required (at 100% efficiency) is
\frac{1}{2} (8 \,  \frac{m}{s} )^{2}*(9 \,  \frac{m^{3}}{s} )*(1.18 \,  \frac{kg}{m^{3}}) =  339.84 \, W

The actual power will be higher because 100% efficiency is not possible.

Answer: 339.8 W (nearest tenth)
8 0
4 years ago
Find the area under the standard normal curve between z=0.19 and z=2.18. round your answer to four decimal places, if necessary.
LiRa [457]

The area under the standard normal curve between z=0.19 and z=2.18 is,

P(0.19<z<2.18)= 0.4101

<h3>How can we calculate the area under the curve?</h3>

To calculate the The area under the standard normal curve  between z=0.19 and z=2.18, we are using two things,

<u>Step 1</u>: The formula,

P(0.19<z<2.18)= P(Z<2.18)- P(Z<0.19)

<u>Step 2</u>: The statistical values of the area under the curve we get from the picture.

Now we put the known values from the picture in the above formula, we get,

P(0.19<z<2.18)= P(Z<2.18)- P(Z<0.19)

Or, P(0.19<z<2.18)=  0.9854-0.5753

Or, P(0.19<z<2.18)=  0.4101

From the above calculation we can easily conclude that,

The area under the standard normal curve between z=0.19 and z=2.18 is,

P(0.19<z<2.18)= 0.4101

Learn more about the standard normal curve:

brainly.com/question/17088387

#SPJ4

5 0
2 years ago
A beam of 1.0 MHz ultrasound begins with an intensity of 1000 W/m². After traveling 12 cm through tissue with no significant ref
Ksenya-84 [330]

Answer:

Option C

Explanation:

Given:

- Depth of tissue d = 12 cm

- frequency of ultrasound f = 1 MHz

- Input Intensity I_i = 1000 W/m^2

- attenuation coefficient soft tissue a = 0.54

Find:

- Out-put intensity at the required depth

Solution

- The amount of attenuation in (dB) with the progression of depth is given by:

                                     Attenuation = a*f*d

                                     Attenuation = 0.54*12*1

                                     Attenuation = 6.48 dB

- The relation with attenuation and ratio of input and output intensity is given by:

                                     Attenuation = 10*log_10 (I_i / I_o)

                                     6.48 dB = 10*log_10 (I_i / I_o)

                                      I_i / I_o = 10^(0.648)

                                      I_o = 1000 / 10^(0.648)

                                      I_o = 225 W/m^2

- Hence the answer is option C:  I_o = 250 W/m^2  

4 0
4 years ago
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