Which statement describes an advantage of models? Models can be used to communicate and test designs ideas. Models always show the exact size of a system. Models have the ability to develop into complex systems. Models are useful for developing scientific methods.

Answer:

60008.4 J

Explanation:

The mass of each kid = 30 kg

mass of the cart = 20 kg

The speed of the cart down the hill = 30 km/hr = 30 x 1000/3600 = 8.33 m/s

The height of the hill = 80 m

The potential energy of the boys at the top of the hill = mgh

where

m is the total mass of the kids and the cart = (30 x 2) + 20 = 80 kg

g is the acceleration due to gravity = 9.81 m/s^2

h is their height above the ground = 80 m (on the top of the hill)

substituting, we have

potential energy PE = 80 x 9.81 x 80 = 62784 J

At an instance at the bottom of the hill

their kinetic energy = [tex]\frac{1}{2} mv^2[/tex]

where

v is their velocity = 8.33 m/s

m is their total mass = 80 kg

substituting, we have

kinetic energy KE = [tex]\frac{1}{2}*80*8.33^2[/tex] = 2775.6 J

Total work done on the cart is equal to the energy lost by the cart when it reached the bottom of the hill

work done by friction = PE - KE = 62784 - 2775.6 = 60008.4 J

Answer:

[tex]\frac{729\frac{m^{2} }{s^{2} } }{83m}[/tex]≈8.8[tex]\frac{m}{s^{2} }[/tex]

Explanation:

Explanation:

1 L = 1000 cm³

m = ρV

m = (13.6 g/cm³) (1000 cm³)

m = 13,600 g

Answer:

   x_total = 23250 m

Explanation:

This is a uniform motion exercise, the equation that describes the motion is

         v = x / t

the position is

        x = v t

let's reduce the magnitude to the SI system

        v = 85 km / h (1000 m / 1km) (1h / 3600 s) = 23.61 m / s

         t = 0.25 h (3600 s / 1h) = 900 s

let's calculate

         x₁ = v t₁

         x₁ = 23.61   900

         x₁ = 21250 m

The distance from the origin is

         x_total = x_station + x₁

         x_total = 2000 + 21250

         x_total = 23250 m

Answer:

Yes the correct answer is B

Explanation:

Answer:

8 seconds = 72cm

3 seconds = 36cm

6 seconds = 96cm

Explanation:

lab assignment i just took.

Speed is the rate of distance over time. The speed of the cart is as follows:

Let:

[tex]s \to[/tex] speed

[tex]d \to[/tex] distance

[tex]t \to[/tex] time

After 8 seconds

For low fan speed; the distance (d) at 8 seconds is:

[tex]d =576cm[/tex]

Speed (s) is calculated using:

[tex]s = \frac dt[/tex]

[tex]s = \frac{576cm}{8s}[/tex]

[tex]s = 72cms^{-1}[/tex]

Hence, the speed after 8 seconds is [tex]72cms^{-1}[/tex]

After 3 seconds

For medium fan speed; the distance (d) at 3 seconds is:

[tex]d = 108cm[/tex]

The speed (s) is :

[tex]s = \frac dt[/tex]

[tex]s = \frac{108cm}{3s}[/tex]

[tex]s = 36cms^{-1}[/tex]

Hence, the speed after 3 seconds is [tex]36cms^{-1}[/tex]

After 6 seconds

For high fan speed; the distance (d) at 6 seconds is:

[tex]d = 108cm[/tex]

The speed (s) is :

[tex]s = \frac dt[/tex]

[tex]s = \frac{576cm}{6s}[/tex]

[tex]s = 96cms^{-1}[/tex]

Hence, the speed at 6 seconds is [tex]96cms^{-1}[/tex]

Read more about speed at:

https://brainly.com/question/7359669

Answer:

it must move back and forth during sex

Answer:

the light travels at a velocity of [tex]2\,\,10^8 \frac{m}{s}[/tex] in the glass

Explanation:

Recall that the refractive index of a material (n) is defined as the quotient between the speed of light in vacuum (c), and the speed of light in the medium (v). Therefore we can solve for the speed of light in the medium if we know the index of refraction it has:

[tex]n=\frac{c}{v} \\v=\frac{c}{n} \\v=\frac{3\,\,10^8}{1.5} \frac{m}{s} \\v=2\,\,10^8 \frac{m}{s}[/tex]

Answer: 12 mph

Explanation: 36 miles divided by 3 hours would be 12 mph

Answer:

The true statement about the maximum speed of each car will be that the power of each car directly proportional to the speed of each car.

Explanation:

Given that,

Power of first car = 100 watt

Power of second car = 150 watt

Power of third car = 200 watt

We know that,

Power :

The power is directly proportional to the cube of speed.

In mathematically,

[tex]P\propto v^3[/tex]

Where, P = power

v = speed

If the power is increased then the speed will be increase.

We need to find the maximum speed of car

According to question,

The power of car is maximum so the speed of car will be maximum.

For first car,

The power of first car is 100 watt.

So, the speed of first car will be 1000000 m/s.

For second car,

The power of second car is 150 watt.

So, the speed of second car will be 3375000 m/s.

For third car,

The power of third car is 200 watt.

So, the speed of first car will be 8000000 m/s.

Hence, The true statement about the maximum speed of each car will be that the power of each car directly proportional to the cube of speed of each car.

Answer:

B. A metal image of gas molecules as tiny balls

Answer:

B. A mental image of gas molecules as tiny balls

First of all, See the attachment for better understanding[tex].[/tex]

_________________________________

❂ Weight of block A :

➝ mg sin30° = 18

➝ W (1/2) = 18

➝ W = 18×2

➝ W = 36N

❂ Weight of block B :

➝ N sin30° = 18

➝ (Mg cos30°) sin30° = 18

➝ W' (√3/2)(1/2) = 18

➝ W' (√3/4) = 18

➝ W' = 72/√3

➝ W' = 41.61N

Answer:

Water

Explanation:

How do we have water at our disposal, like that's crazy.

Answer:

Boiling Water.

Explanation:

Because there is still kinetic energy in the water. Thus it has heat energy.

Answer:

The total distance moved by the car is 80 metres

Explanation:

Given

North = 30 meters

South = 50 meters

Required

Determine the distance

Distance is a scalar quantity and hence, the total distance is the summation of distance moved in both directions

i.e.

[tex]Total\ Distance = North + South[/tex]

[tex]Total\ Distance = 30\ metres + 50\ metres[/tex]

[tex]Total\ Distance = 80\ metres[/tex]

Hence;

The total distance moved by the car is 80 metres

Answer:

A System

Explanation:

There are many systems including the circulatory and nervous system where multiple organs work together to perform a job.

Answer:

A

Explanation:

It is deemed to be incorrect because velocity deals with displacement. Or in more simple terms, distance in a specified direction.

While moving round the track, the direction keeps changing, so to say and the velocity vector changes constantly.

Speed on the other hand, is a scalar quantity that doesn't bother about nor depends on the direction being taken by the car.

that's all, I hope you understand it all

Answer:

 v_A = 6 m/s , v_B = 0 m/s ,  v_C = - 4 m/s , v_D = -4 m/s ,     v_E = 2.66 m / s

Explanation:

For this exercise we use the definition of average velocity in each segment

         v_average = (x₂-x₁) / Δt

segment A of the graph you take the value of distance and time

x₁ = 0 m     t₁ = 0 s

x₂ = 60 m   t₂ = 10 s

using the average velocity equation and calculate

         v_A = (60-0) / (10-0)

         v_A = 6 m / s

Segment B

x₁ = 60m

x₂ = 60 m

since the displacement variation is zero (particle stopped) the velocity is zero

         v_B = 0 m / s

Segment C and D

x₁ = 60 m    t1 = 15 s

x₂ = -40 m  t2 = 40 s

        v_C = (-40 -60) / (40 -15)

        v_C = - 4 m / s

Segment D

how is the same line

         v_D = -4 m / s

Segment E

x₁ = -40 m  t₁ = 40 s

x₂ = 0 m    t₂ = 55 s

         v_E = (0- (-40)) / (55 -40)

         v_E = 2.66 m / s

Answer:

The  relation is  [tex]T = 2\p \sqrt{\frac{l}{g} }[/tex]

Explanation:

Generally the mathematically relation showing the relationship between the period(T), the constant (g) and  the length(l) is

     [tex]T = 2\p \sqrt{\frac{l}{g} }[/tex]  

Answer:

D) The contraction of objects in space

Explanation:

A) Expansion of the universe as originated from the Big Bang is an important evidence, as B) the Cosmic microwave background which is thought to be left over from the Big Bang. The right proportion of hydrogen and helium as unprocessed material that has been detected as the basic elements from where the universe started.

The only out of context option is option D

Answer:

When we run a piece of paper with the oil in our head with the help of a comb produces electrostatic force.

Balloons get attracted to another balloon when one of them are rubbed with hair.

Explanation:

Those are 2 examples of electrostatic force.

Answer:

accuracy refers to the deviation of a measurement from a standard or true value of the quantity being measured

Answer:

1. 50 m/s 2. 10 ft/min 3. 50 miles/hour 4. 10 m/s

Explanation:

We are required to calculate the speed in each instant

Since speed = distance/time,

1. For the doctor, speed = distance/time = 100 m/20 s = 50 m/s

2. For the duck, speed = distance/time = 20 feet/ 2 min = 10 ft/min

3. For the dude who flew, speed = distance/time = 100 miles/ 2 hours = 50 miles/hour = 50 mi/h

4. For Dave who rolled down the hill, speed  = distance/time = 300 metres/ 30 s = 10 metres/ second = 10 m/s

Answer:

Option (D) is correct.

Explanation:

The balloon lands horizontally at a distance of 420 m from a point where it as released.

Velocity of air balloon along +X axis =10 m/s

velocity of ball=4 m/s along + X axis

the velocity of balloon gets added to the velocity of ball. So the resultant velocity of the balloon=10+4 = 14 m/s

time taken= 30 s

The distance traveled is given by d= v t

d= 14 (30)

d= 420 m

Thus the balloon lands horizontally at a distance of 420 m from a point where it as released.

Answer:

nngh have

bjruh hjrhhj be rnrnnrnrnnnrnjrjnnnnnnnnrnrn n n and I was nrn

Explanation:

jbbbbbhhhjjnnnnnnnnnnjhvcc

Explanation:

Explanation:

Given data

velocity v= 25m/s

The time it takes to put on brake t= 0.3s

the distance covered when the  brake was put on is

v=s/t

s= v*t

s= 25*0.3s

s= 7.5m

hence the distance covered is 7.5m

Also the rate of decrease in aceleration is 5m/s^2

we can also calculate the distance covered at this rate

v^2=u^2+2as

25^2= 0+2*5*s

625=10s

divide both sides by 10

s=625/10

s= 62.5m

The total  distance covered between putting on the brakes and decelareation is  7.5+62.5= 70m

Given that the tree is 75m ahead, the car would not hit the tree

Answer:

The work done is 2.94 Nm.

Explanation:

First, you have to find the force of a brick layer using the formula, Force = mass×gravity :

[tex]f = m \times g[/tex]

[tex]let \: m = 10,g = 9.8[/tex]

[tex]f = 10 \times 9.8[/tex]

[tex]f = 98N[/tex]

Given that the force of a brick layer is 98N. Next, you have to apply work done formula, Work done = force×distance :

[tex]w.d = f \times d[/tex]

[tex]let \: f = 98,d = 0.03m[/tex]

[tex]w.d = 98 \times 0.03[/tex]

[tex]w.d = 2.94Nm[/tex]

Answer:

Option D - 0.2 s

Explanation:

We are given;

Initial velocity; u = 7 m/s

Height of table; h = 1.8m

Now,since we want to find the time the car spent in the air, we will simply use one of Newton's equation of motion.

Thus;

h = ut + ½gt²

Plugging in the relevant values, we have;

1.8 = 7t + ½(9.8)t²

4.9t² + 7t - 1.8 = 0

Using quadratic formula to find the roots of the equation gives us;

t = -1.65 or 0.22

We can't have negative t value, thus we will pick the positive one.

So, t = 0.22 s

This is approximately 0.2 s