a machine
of efficiency of 70% is used to raise
a body of
mass 80 kg through
a vertical distance of 3m in
40 seconds. Calculate the power input. (Take g = 10 m/s²)​

Answer:

First answer to the first question is Two people pulling a rope with the same force in a opposite direction.  The other one would be 2.72N        

Explanation:

Hope this helps you :)

Answer:

a) ll and Ill only

Explanation:

Let the mass of the wrench = m

and the mass of the astronaut = M

Initially, the velocity of the astronaut and wrench are zero.

The astronaut throws the wrench in one direction and subsequently recoils back with a velocity in the opposite direction.

Let v and V be the velocity of the wrench and the velocity of the astronaut respectively.

In space, there is no external force acting, the momentum must be conserved.

So, m(0)+M(0)=m(v)+M(V)

So, 0=mv+MV

[tex]\Rightarrow mv=-MV[/tex] ...(i)

Here, the momentum of the wrench = mv, and the momentum of the astronaut= MV. The negative sign showing that both the momentum are in opposite direction.

Therefore, the momentum of the wrench is equal and opposite to the momentum of the astronaut.

According to Newton's second law, the rate of change of momentum = applied force.

Let it take [tex]\Delta t[/tex] seconds to change the momentum.

So, for the wrench

[tex]m(v-0)/\Delta t= F_w \\\\\Rightarrow m(v-0)=F_w\Delta t \\\\\Rightarrow mv=F_w\Delta t \cdots(ii)[/tex]

Here, [tex]F_w\Delta t[/tex] is the impulse applied to the wrench.

Similarly, for the astronaut

[tex]M(-V-0)/\Delta t= F_a[/tex] [negative sign (-V) for opposite direction]

[tex]\Rightarrow M(-V-0)=F_a\Delta t \\\\\Rightarrow -MV=F_a\Delta t[/tex]

Here, [tex]F_a\Delta t[/tex] is the impulse applied to the astronaut.

So, the impulse on the astronaut.

By using equations (i) and (ii)

[tex]F_a\Delta t=F_w\Delta t[/tex]

Therefore, the impulse applied to the wrench is equal and opposite to the impulse applied to the astronaut.

Hence, option (a) is correct.

Answers: 1) 3 kg m²

                2) 2.88 kg m²

Explanation: Question 1

                      I = m(r)²+ M(r)²

                      I = 1.2 kg × (1 m )² +1.8 kg ×(1 m )²

                    ∴  I =   3 kg m²

                      Question 2

ACCORDING TO THE DIAGRAM DRAWN FOR QUESTION 2

we have to decide where the center of gravity (G) lies and obviously it should lie somewhere near to the greater mass. (which is 1.8 kg). Since we don't know the distance from center of gravity(G) to the mass (1.8 kg) we'll take it as 'x' and solve!!

moments around 'G'

F₁ d ₁ = F₂ d ₂

12 (2-X) = 18 (X)

24 -12 X =18 X

∴  X = 0.8 m

∴ ( 2 - x ) = 1.2 m

∴ Moment of inertia (I) going through the center of mass of two masses,

⇒ I = m (r)² +M (r)²

⇒ I = 1.2 × (1.2)² + 1.8 × (0.8)²

⇒ I = 1.2 × 1.44 + 1.8 × 0.64

⇒ I = 1.728 + 1.152

⇒ ∴ I = 2.88 kg m²

∴ THE QUESTION IS SOLVED !!!

Considering the Ohm's law, the correct answer is option B. the current is 0.048 A.

The flow of electricity through an object, such as a wire, is known as current (I). Its unit of measure is amps (A). So the current is a measure of the speed at which the charge passes a given reference point in a specified direction.

The driving force (electrical pressure) behind the flow of a current is known as voltage and is measured in volts (V) (voltage can also be referred to as the potential difference or electromotive force). That is, voltage is a measure of the work required to move a charge from one point to another.

Resistance (R) is the difficulty that a circuit opposes to the flow of a current and it is measured in ohms (Ω).

Ohm's law establishes the relationship between current, voltage, and resistance in an electrical circuit.

This law establishes that the intensity of the current that passes through a circuit is directly proportional to the voltage of the same and inversely proportional to the resistance that it presents.

Mathematically, Ohm's law is expressed as:

[tex]I=\frac{V}{R}[/tex]

Where I is the current measured in amps (A), V the voltage measured in volts (V); and R the resistance that is measured in ohms (Ω).

In this case, you know that the voltage between two points in a circuit is 3.6 V and the resistance between the points is 75 Ω.

Replacing in the Ohm's Law:

[tex]I=\frac{3.6 volts}{75 ohm}[/tex]

Solving:

I= 0.048 amps

Finally, the correct answer is option B. the current is 0.048 A.

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Answer and Explanation:

--> MRI (Magnetic Resonance Imaging) is an imaging technique that involves the use of radio waves and magnetic field to generate high detailed images of the human body. It's clinical applications includes:

• Bone and joint MRI:  these are done to check for bone and joint problems such as bone marrow disorders, arthritis, or bone tumours.

• A Spine MRI: This is used to investigate the spinal disc and innervations for disorders such as spinal tumours.

• Chest MRI: This is used to detect abnormalities of the heart, heart valves and coronary arteries.

--> X-RAY: These are electromagnetic waves of short wavelength with high penetrating power. They are produced when fast moving electrons strike a mass of heavy atoms such as those of metals. It's applications includes:

• They are used to detect hidden cracks in materials.

• They are used to show broken bones in human body.

• They are used in the study of internal structures of crystals.

• In agriculture, x-rays are used in killing germs.

--> ULTRASOUND: This makes use of high frequency sounds to detect abnormalities in the human body. An ultrasound machine transmits sound waves into the body which are reflected at the surfaces between the tissues of different density. It can also be used in different disciplines such as imaging, cleaning, mixing, navigation and communication   It's applications includes:

•. Detection of Cracks: when applied on metallic surface under investigation, high frequency sound wave reflects back which and be predicted and recorded.

--> INFRARED RADIATION: This is a type of electromagnetic radiation with wavelength longer than visible light. It is visible to the human eye and most heated surfaces transmits infrared radiation. It's applications includes:

• it is used for the purpose of sensing and detection. For example the night vision goggles and infrared cameras. Remote control makes use of infrared light waves to change channels in the television.

Answer:

[tex]l_o=550.055\ cm[/tex]

Explanation:

Given that,

Length of a street bridge, l = 5.5 m

The coefficient of bridge, [tex]\alpha =0.00001 ^0 C[/tex]

We need to find how much will it expand when temperatures is by 10°C.

The change in length per unit original length is given by :

[tex]\dfrac{\Delta l}{l}=\alpha \Delta T\\\\\Delta l = l\alpha \Delta T\\\\=5.5\times 0.00001 \times 10\\\\\Delta l=0.00055\\\\(l_o-l)=0.00055\\\\l_o=0.00055+5.5\\\\=5.50055\ m\\\\l_o=550.055\ cm[/tex]

Hence, the length will expanded 550.055 cm.

Answer:

In physics, the weber is the SI derived unit of magnetic flux. A flux density of one Wb/m2 (one weber per square metre) is one tesla.

Hope it helps !

Answer:

Weber unit of magnetic flux in the international system of units (SI), defined as the amount flux that, linking an electrical circuit of one turn (one loop of wire) , produces in it an electromotive force of one volt as the flux is reduced to zero as a uniform rate in one second .

it was named in honour of the 19th century German physicist Wilhelm Eduard Weber

Answer: C- The planets appeared to move backward in the sky occasionally.

Answer:

8 is c and 9 is b it is shown though the practice as god lol

Question 8

The net force acting on the cart is:

F = 150 N - 90 N

F = 60 N

Question 9

By the Newtons second law:

F = ma

Solving for a:

a = F/m

a = 60 N / 30 kg

a = 2 m/s²

Answer:

When an object moves with a constant speed in a circular path, then its motion is called as Circular motion.

Examples of Uniform Circular Motion :--

The moon moves in uniform circular motion around the earth.

A stoned tied to a thread and rotated in circular motion.

An athlete running on a circular track.

A satellite revolving around Earth.

A force may cause an object to turn about a pivot. The turning effect of a force is called the moment of the force. Moments act about a pivot in a clockwise or anticlockwise direction.

Answer:

A force may cause an object to turn about a pivot. The turning effect of a force is called the moment of the force. Moments act about a pivot in a clockwise or anticlockwise direction.

Explanation:

Answer:

PLEASE MARK AS BRAINLIEST!!

Explanation:

A getting passenger getting down from a moving bus, falls in the direction of the motion of the bus. This is because his feet come to rest on touching the ground and the remaining body continues to move due to inertia of motion.

Answer:

When the person steps on the ground, his feet do not move but his upper body moves in the direction of the bus due to inertia of its motion. Since his upper body moves in the forward direction and his lower body does not move, the person falls in the forward direction.

Answer:

β = 114 db

Explanation:

The intensity of sound in decibles is

          β = 10 log [tex]\frac{I}{I_{o}}[/tex]

in most cases Io is the hearing threshold 1 10-12 W / cm²

let's calculate the intensity of each instrument

            I / I₀ = 10 (β / 10)

            I = I₀ 10 (β / 10)

trumpet

            I1 = 1 10⁻¹² 10 (94/10)

            I1 = 2.51 10⁻³ / cm²

Thrombus

           I2 = 1 10⁻¹² 10 (107/10)

           I2 = 5.01 10-2 W / cm²

low

           I3 =1 1-12    (113/10) W/cm²

            I3 = 1,995 10-1 W / cm²

when we place the three instruments together their sounds reinforce

           I_total = I₁ + I₂ + I₃

           I_ttoal = 2.51 10-3 + 5.01 10-2 + ​​1.995 10-1

           I_total = 0.00251 + 0.0501 + 0.1995

           I_total = 0.25211 W / cm²

let's bring this amount to the SI system

         β = 10 log (0.25211 / 1 10⁻¹²)

           β = 114 db

Answer:

i think the red runner travels greater distance ie.40 m

Explanation:

although ,the blue one travels 21 m but in the backward direction .so the correct ans is "the red runner travels 40 m"

Answer:

Explanation:

When the puck is sliding on the ice, there is no force being exerted on the puck to keep it moving forward. Instead, inertia keeps the puck moving forward. Friction between the puck and the ice gradually slows the puck down. You hit a hockey puck and it slides across the ice at nearly a constant speed

At constant speed and varying position of the hockey puck, implies a change in the velocity of the hockey puck and net force is acting on it to keep it in motion.

According to Newton's second law of motion, the force applied to a an object is directly proportional to the product of mass and acceleration of the object.

F = ma

Acceleration is the change in the velocity of an object per change in time of motion.

Thus, we can conclude that at constant speed and varying position of the hockey puck, implies a change in the velocity of the hockey puck and net force is acting on it to keep it in motion.

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Answer:

Except in the crust, the interior of the Earth cannot be studied by drilling holes to take samples. Instead, scientists map the interior by watching how seismic waves from earthquakes are bent, reflected, sped up, or delayed by the various layers.

Explanation:

Answer:

Explanation:

Loss of potential energy but a gain in kinetic (becasue its falling)

Answer:

There is a loss of potential energy and a gain of kinectic

Explanation:

Answer:

A. The sum of all the forces acting on an object.

Answer:

distance ; time

Explanation:

wavelength is in metres [m]

period is in seconds [s]

Answer:

the nucleus is the size of an apple, approximately 5 cm of radius e, the atom has a radius of R = 5 cm 104 = 50000 cm = 50 km

Explanation:

In the Rutherford experiments it was proved that the atomic nucleus has the volume 10-4 the volume of the atom.

If we make a scale design in which the nucleus is the size of an apple, approximately 5 cm of radius e, the atom has a radius of R = 5 cm 104 = 50000 cm = 50 km

This shows that almost the entire volume of the atom is empty.

This question is incomplete, the complete question is;

A high-resistance material is used as an insulator between the conductors of a length of coaxial cable. The resistance material, which forms a hollow tube, has an inner radius a and an outer radius b, and the insulator provides a resistance R between the conductors. If a second insulator, made of the same material and having the same length, is made with double both the inner radius and the outer radius of the first, what resistance would it provide between the conductors

a) (In2)R

b) 4R

c) R/(In2)

d) 2R

e) R

Answer: Option e) R is the correct answer.

Explanation:

Given that;

Inner radius = a

Outer radius = b

Conical Cylinder

∫dR = ∫(edr/2πrL)

R = e/2πL In e |ᵇₐ

R = e/2πL In(b/a) ------------- let this be equation 1

Taking a look at the second cone

a' = 2a

b' = 2a

R' = e/2πL In(2b/2a)

{L = L'}

R' = e/2πL In(b/a) -------let this be equation 2

now lets compare the two equation

R = e/2πL In(b/a)

R' = e/2πL In(b/a)

so R' = R

Therefore Option e) R is the correct answer.

Answer:

Wave B has the longest wavelength

Explanation:

The wavelength of a wave is the distance between two consecutive points that are in phase.

The wavelength of a wave is also defined as the distance between successive crests or troughs along the z-axis.

A crest is the point of maximum upward displacement whereas a trough is a point of maximum downward displacement.

Comparing the three waves A, B and C over a unit distance.

Wave A:

Wave A has three crests and two troughs. The wave begins and ends at the rest position. There are 2½ successive points in phase in wave A

Therefore, the wavelength = 1/2.5 = 0.4

Wave B:

Over a unit distance, wave B has two crests and one trough. The wave begins at the rest position and ends at the top of a crest. There are 1¼ successive points in phase in wave B

Therefore, the wavelength = 1/1¼ = 0.8

Wave C:

Over a unit distance, wave C has four crests and four troughs. The wave begins and ends at the rest position.

There are 4 successive points in phase in wave B

Therefore, the wavelength = 1/4 = 0.25

Therefore, wave B has longest wavelength

Answer:

1.62 m/s

Explanation:

Wavelength of the water wave= 54 m

The frequency is 0.03 Hz

Therefore the velocity can be calculated as follows

Velocity= frequency × wavelength

= 0.03 × 54

= 1.62 m/s

Question 4

B. Toby is correct because the rock is experiencing a negative acceleration, causing its positive velocity to decrease until the rock reaches a velocity of O m/s before becoming negative.

Question 5

At the maximum height, velocity is 0, so:

v = v₀ - gt

0 = 14.75 - 9.8t

t = 14.75/9.8

t = 1.5 s    (OPTION A)

4). In the given situation, the assertion that could be made regarding Toby would be:

B). Toby is correct because the rock is experiencing a negative acceleration, causing its positive velocity to decrease until the rock reaches a velocity of O m/s before becoming negative.

5). The time that would be taken by the rock to attain its greatest height would be:

1.5 second

4). Tobby correctly states as rock would be undergoing a -ve acceleration which leads its +ve velocity to fall by the time rock attains the velocity of 0 m/s.

Thus, option B is the correct answer.

5). Given that,

Initial velocity([tex]v_{0}[/tex]) = 14.75 m/s

As we know,

Velocity remains 0 m/s at the greatest height,

So,

Velocity(v) [tex]= v_{0} - gt[/tex]

where

[tex]0 = 14.75 - 9.8t[/tex]

⇒ [tex]t = 14.75/9.8[/tex]

 ∵ [tex]t = 1.5 s[/tex]

Learn more about "Velocity" here:

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Answer:10 m/s

Explanation:

A 100 kg gymnast comes to a stop after tumbling. Her feet do 5,000 J of work to stop her. The girl's velocity when she began to stop is 10 m/sec.

When an item is moving, its velocity is the rate at which its direction is changing as seen from a certain point of view and as measured by a specific unit of time. Velocity is vector quantity.

Uniform motion an object is said to have uniform motion when object cover equal distance in equal interval of time within exact fixed direction. For a body in uniform motion, the magnitude of its velocity remains constant over time. Here in the question velocity is changing by using work energy theorem we have,

work done = change in kinetic energy

5000 = (.5).m.v² , where v is velocity.

5000 = (.5).100.v²

v = 10 m/sec

A 100 kg gymnast comes to a stop after tumbling. Her feet do 5,000 J of work to stop her. The girl's velocity when she began to stop is 10 m/sec.

To learn more about velocity refer the link:

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Answer:

I guess the Ans for second one is gravitational force