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2 years ago

Explain why steel is mor dense than water

Physics

2 answers:

natta225 [31]2 years ago

7 0

Steel is more dense because it’s heavy while water is light

evablogger [386]2 years ago

7 0

Steel is a metal and has high density than water . Water is also a mixture of the lightest gas in the world mixed oxygen .

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Six dogs pull a two-person sled with a total mass of 220 kg. The coefficient of kinetic friction between the sled and the snow i

irina [24]

Answer:

a) 2457J

b) 558W

c) 337N

Explanation:

Assuming dogs started from rest.

$v=a*t\\t=\frac{a}{v}\\v=12\frac{km}{h}\frac{1000m}{km}*\frac{1h}{3600s}\\\\v=3.3m/s\\\\t=\frac{3.3m/s}{0.75m/s^2}\\t=4.4s$

and the displacement is given by:

$d=\frac{1}{2}*a*t^2\\d=7.3m$

Using the energy conservation formula:

$K_i+U_i+W_d+W_f=K_f+U_f$

Because the motion started from rest the initial kinetic energy is zero, the motion occurred in-ground level so the gravitational energy is zero too.

the work done by the friction force is given by:

$W_f=F_f*d*cos(\theta)\\W_f=\µ*m*g*d*cos(180)\\W_f=0.08*220kg*9.8m/s^2*7.3m*(-1)\\W_f=-1259J$

so:

$W_d=\frac{1}{2}*220kg*(3.3m/s)^2+1259J\\W_d=2457J$

The power is given by:

$P=\frac{W}{t}\\\\P=\frac{2457J}{4.4s}\\\\P=558W$

and the force exerted by the dogs:

$W_d=F_d*d*cos(\theta)\\F_d=\frac{W_d}{d*cos(0)}\\\\F=\frac{2457J}{7.3m*(1)}\\\\F=337N$

4 0

2 years ago

An air conditioner operating between 93°F and 70°F is rated at 4000 Btu/h cooling capacity. Its coefficient of performance is 27

lana [24]

Answer: $P_{in}=0.25\ Hp$

Explanation:

Given

Operating temperatures are

$T_L=70^{\circ}F\approx 294.261\ K$

$T_H=93^{\circ}F\approx 307\ K$

$COP$ is $27\%$ of Carnot refrigerator

$COP_{carnot}=\dfrac{T_L}{T_H-T_L}$

$COP_{carnot}=\dfrac{294.261}{307-294.261}$

$COP_{carnot}=\dfrac{294.261}{12.74}$

$COP_{carnot}=23.09\approx 23.1$

actual $COP=0.27 \times COP_{carnot}$

$COP_{actual}=6.237$

Also, $COP=\dfrac{\text{Desired effect}}{\text{Power in}}$

$6.237=\frac{4000}{P_{in}}$

$P_{in}=\frac{4000}{6.237}=641.33\ Btu/h$

$P_{in}=0.25\ Hp$

6 0

2 years ago

A crate resting on a rough horizontal floor is to be moved horizontally. The coefficient of static friction is 0.36. To start th

luda_lava [24]

Answer:

Explanation:

The direction of force will be in upward direction making an angle of θ with the vertical .

Reaction force R = mg - F cosθ

Friction force = μR

= .36 (mg - F cosθ )

Horizontal component of applied force

= F sinθ

For equilibrium

F sinθ = .36 (mg - F cosθ)

F sinθ + .36 F cosθ =.36 mg

F (sinθ + .36 cosθ) = .36 mg

F R( cosδsinθ +sinδ cosθ) = .36 mg ( Rcosδ = 1 . Rsinδ= .36 )

F R sin( θ+δ ) = . 36 mg

F = .36 mg / Rsin( θ+δ )

For minimum F , sin( θ+δ ) should be maximum

sin( θ+ δ ) = sin 90

θ+ δ = 90

Rsinδ / Rcosδ = .36

δ = 20⁰

θ = 70⁰ Ans

5 0

3 years ago

Compare the Summer Solstice with the Autumn Equinox. Justify your response in two or more complete sentences.

ryzh [129]

Midway between the two solstices we have equinoxes – Vernal Equinox in March and Autumnal Equinox in September. ... After this time, the Earth's northern axis is tilted more and moretowards ... Then on Summer Solstice, the Sun will reach its farthest north position in the sky

4 0

2 years ago

Read 2 more answers

Calculate the kinetic energy in joules of an automobile weighing 2135 lb and traveling at 55 mph. (1 mile = 1.6093 km, 1 lb = 45

victus00 [196]

Let's convert the speed to m/s: speed = (55 mph) (1609.3 m / mile) (1 hour / 3600 seconds) speed = 24.59 m/s Let's convert the mass to kilograms: mass = (2135 lb) (0.45359 kg / lb) mass = 968.4 kg We can find the kinetic energy KE: KE = (1/2) m v^2 KE = (1/2) (968.4 kg) (24.59 m/s)^2 KE = 292780 joules The kinetic energy of the automobile is 292780 joules.

4 0

2 years ago