A train travels a 400-km route and makes five stops in seven hours. Which equation is used to calculate the train’s average speed?


A.
Average speed = Sum of instantaneous speeds


B.
Average speed = Total distance x Total time


C.
Average speed = Total distance + Total time


D.
Average speed = Total distance ÷ Total time

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

Answer:A

Explanation:

Hdjfjdjfjr

A liquid thermometer can be used to test for fevers. When body temperature increases, the liquid inside the thermometer expands and rises to show a higher temperature reading, the explanation that describes the change in the thermal energy,

The thermometer tip is heated by conduction with the person's body. The particles of the thermometer tip then transfer heat by conduction with the liquid inside of it. The particles inside the liquid then convect heat causing the warmer particles to speed up, expand, and rise.

It can be defined as the form of the energy in which heat is transferred from one body to another body due to their molecular movements, thermal energy is also known as heat energy.

Conduction with the subject's body heats the thermometer's tip. The liquid inside the thermometer is subsequently heated by conduction between the particles of the thermometer tip. The warmer particles then accelerate, expand, and ascend as a result of the heat convecting through the liquid's particles.

Thus, the correct answer is option D.

Learn more about thermal energy from here

brainly.com/question/3022807

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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:

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

Explanation:

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:

I think it would be muscle

Explanation:

bones strengthened by calcium

aerobics is more of a gymnastical exercise

leaving a muscle strengthen

Answer:

Technically all 3

Explanation:

Include activities that make their hearts beat faster, build muscles (like climbing or doing push-ups), and strengthen bones (like running or jumping).

Traditional pushups are beneficial for building upper body strength. They work the triceps, pectoral muscles, and shoulders. When done with proper form, they can also strengthen the lower back and core by engaging (pulling in) the abdominal muscles. Pushups are a fast and effective exercise for building strength.Jun 22, 2018

Aerobic exercise (also known as cardiovascular exercise) builds your endurance. Anaerobic exercise typically means activities such as weightlifting and push-ups and sit-ups, which builds muscle and physical strength through short bursts of strenuous activity.

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]  

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:

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

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:Qualitative

Explanation:

Answer:

B on edgen

Explanation:

The water in pot X has more kinetic energy than the water in pot Y.

Answer:

the water in pot x has more kenetic energy.

Explanation:

not sure if its the answer. just found it on quizlet.

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:

Explanation:

time= distance/speed

20km/ 15km/h

= 1 1/3 hours (4/3 in mixed fraction)

Answer:

B).315mph

Explanation:

Let the speed of the plane = p

Let the speed of the wind = w

Set up the system equation as;

                                     Relative V:               Time:                          Distance:

in wind direction:          p + w                         2                                  700

against wind:                 p - w                         2.5                                700

2(p + w) = 700

2.5(p - w) = 700

2p + 2w = 700

2.5p - 2.5w = 700

2.5  x:     5p + 5w = 1750

2  x:        5p - 5w = 1400

10p = 3150

p = 315 mph

Therefore, he speed of the plane in still air is 315 mph

Answer: The SI unit

Explanation: The SI units are used to describe the distance an object moves

Explanation:

1 L = 1000 cm³

m = ρV

m = (13.6 g/cm³) (1000 cm³)

m = 13,600 g

Explanation:

Hey there!!

Here, Given is,

Efficiency = 75%

VR = no. of pulleys = 5

Now,

[tex]effeciency = (\frac{ma}{vr} ) \times 100\%[/tex]

[tex]75\% = \frac{ma}{5} \times 100\% [/tex]

100% ma = 75%×5

[tex]ma = \frac{75\% \times5}{100\%} [/tex]

[tex]ma = \frac{375\%}{100\%} [/tex]

Therefore, MA is 3.75.

Hope it helps...

Answer:

MA=3.75

Explanation:Given that, E=75%, VR=no. of pulley=5

NOW,

E=(MA/VR)*100%

75%=(MA/5)*100%

MA=(75%*5)*100%

MA=375%/100%

∵MA=3.75

Answer:

Explanation:

Using one of the equation of motion v = u + at where;

v is the final velocity = 0m/s (the ball comes to rest after throw)

u is the initial velocity = 46m/s

a is the acceleration = -5m/s² (the body decelerates)

t is the time taken by the ball in air

substituting the given parameters into the formula to get t, we will have;

0 = 46 +(-5)t

0 = 46 - 5t

subtract 46 from both sides

0-46 = 46-5t-46

-46 = -5t

Divide both sides by -5

-46/-5 = -5t/-5

t = 46/5

t = 9.2seconds

Hence it will take the ball 9.2seconds in the air before coming to rest.

Answer: 9.2sec

Explanation. 9.2sec

Answer:

All the objects experience the same acceleration

Explanation:

According to Newton's law of universal gravitation, we have the gravitational force F given by the relation;

[tex]F=G \times \dfrac{M_1 \times m_{2}}{R^{2}}[/tex]

Where;

G = The universal gravitational constant

M₁ = The mass of the Earth

m₂ = The mass of the object in the Earths gravitational field

R = The radius of the Earth

Therefore, we have;

[tex]F= m_2 \times a = G \times \dfrac{M_1 \times m_{2}}{R^{2}}[/tex]

Which gives;

[tex]a = G \times \dfrac{M_1 }{R^{2}} \ which \ is \ a \ constant = 9.80665 \ m/s^2, \ known \ as \ g, \ which \ is \ \\the \ (acceleration \ due \ to \ gravity)\\[/tex]Therefore, based on the above calculation, all three object will have the same acceleration due to gravity, g, when air resistance is ignored.

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:

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:

0 [tex]\leq[/tex] t [tex]\leq[/tex] 40

Explanation:

Apex :)

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:

It will take the plant [tex]4\frac{4}{9}[/tex] days or 4.44 days to grow to a height of 200 inches tall.

Explanation:

From the question, the rate at which the species of the bamboo tree grows is 36 inches per day.

To determine how long it would take a plant 40 inches tall initially to grow at this rate (that is, 36 inches per day) to a height of 200 inches.

This means we will calculate the number of days it will take the plant to grow additional 160 inches ( 200 inches - 40 inches) at this rate.

Now,

If the plant grows 36 inches in 1 day

then it will grow 160 inches in x days

x = (160 inches × 1 day) / 36 inches

x = 160 / 36

x = [tex]4\frac{4}{9}[/tex] days or 4.44 days

Hence, it will take the plant [tex]4\frac{4}{9}[/tex] days or 4.44 days to grow to a height of 200 inches tall.

Answer: 12 mph

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

Answer:

Matter

Explanation:

Any type of material is a matter. It can be anything that occupies space and have mass. It is a composition of atoms which in term is made up of electrons, protons and neutrons. All particles in our universe is matter because everything has some mass and it occupies space.

Answer:

Anything that has mass and occupies space

Explanation:

Just took the test

Answer:

Boiling Water.

Explanation:

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