If Johnny won a 300 meter race in 40 seconds, his speed would be ?

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: 12 mph

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

Answer:A

Explanation:

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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:

Boiling Water.

Explanation:

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

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]

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:

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:

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

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:Qualitative

Explanation:

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:

it must move back and forth during sex

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.

Explanation:

1 L = 1000 cm³

m = ρV

m = (13.6 g/cm³) (1000 cm³)

m = 13,600 g

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:

B. A metal image of gas molecules as tiny balls

Answer:

B. A mental image of gas molecules as tiny balls

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:

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:

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:

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

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:

Explanation:

time= distance/speed

20km/ 15km/h

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

Answer:

Yes the correct answer is B

Explanation:

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:

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

Explanation:

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:

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:

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.