A powerlifter deadlifts a 365 lb (167 kg) barbell to a height of 0.85 m, and then lowers the bar, applying a constant upward force. The bar reaches the ground with a speed of 2 m/s. What was the work done by the powerlifter in lowering the bar to the ground (in J)
Answers
A powerlifter deadlifts a 365 lb (167 kg) barbell to a height of 0.85 m, and then lowers the bar, applying a constant upward force. The bar reaches the ground with a speed of 2 m/s. The work done by the powerlifter in lowering the barbell to the ground is approximately -1963.49 J.
To calculate the work done by the powerlifter in lowering the bar to the ground, we can use the work-energy principle. According to this principle, the work done is equal to the change in the object's mechanical energy.
The mechanical energy consists of two components: the gravitational potential energy and the kinetic energy.
The gravitational potential energy (PE) is given by the equation:
PE = m × g × h
where m is the mass of the barbell, g is the acceleration due to gravity, and h is the height through which the barbell is lowered.
The kinetic energy (KE) is given by the equation:
KE = (1/2) × m × v^2
where v is the final velocity of the barbell (2 m/s).
Since the barbell is lowered, the work done by the powerlifter is negative. Therefore, the work done (W) is given by:
W = -(PE + KE)
Substituting the given values:
m = 167 kg
g = 9.8 m/s^2
h = 0.85 m
v = 2 m/s
PE = (167 kg) × (9.8 m/s^2) × (0.85 m)
KE = (1/2) ×(167 kg) × (2 m/s)^2
PE ≈ 1406.49 J
KE ≈ 557 J
W = -(1406.49 J + 557 J)
W ≈ -1963.49 J
Therefore, the work done by the powerlifter in lowering the barbell to the ground is approximately -1963.49 J. The negative sign indicates that work is done against the upward force applied by the powerlifter.
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Related Questions
Two units of measurement for energy are calories and joules. The measurement of 355 J is the same amount of energy as ___________.
Answers
Two units of measurement for energy are calories and joules. The measurement of 355 J is the same amount of energy as 84.84 calories.
Energy in physics is the ability to perform work. Different shapes, such as potential, kinetic, thermal, electrical, chemical, radioactive, etc., may be assumed by it. Other examples of energy being transferred from one body to another include heat and work. Energy is always distributed after it has been transported in accordance with its type. Thus, heat transfer could result in thermal energy, whereas work could result in mechanical energy.
Motion is a trait shared by all forms of energy. For instance, if a body is moving, it has kinetic energy. Due to the object's design, which incorporates potential energy, a tensioned object, like a spring or bow, has the ability to move even when at rest.
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A _____ is a series of events and activities with no slack time. a. risk path b. foundation path c. baseline path d. critical path.
Answers
The D. critical path is a series of events and activities with no slack time.
It is a path that defines the longest duration required to complete a project. It is significant in the project management methodology as it helps the project manager establish a timeline for the project while also identifying the activities that are most critical to the project's completion. If an activity on the critical path takes longer than anticipated, the whole project will be delayed, and if an activity is completed earlier than expected, then it might not be worth it to continue the project, and the client might not be willing to pay for it.
The critical path analysis allows managers to identify and control the critical factors that can impact a project's success, enabling them to focus on the most important areas and make informed decisions about the project. So the correct answer is D. critical path, is a series of events and activities with no slack time.
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is this kinetic or potential energy: A baseball has reached its highest point after being hit toward the top of the stadium
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Potential is when it’s not in motion but has the potential. For example, if you were going to drop a pencil, it would have potential energy while in your hand but kinetic when it’s falling.
Over the course of a year, stars should appear to move back and forth, with stars closer to us moving a larger distance.
Answers
This is a description of the apparent motion of stars due to Earth's axial tilt and revolution around the sun.
What is distance?Distance is a scalar quantity that represents the magnitude of separation between two points in space. It is the length of the path between two points, and is measured in units such as meters, kilometers, miles, etc. Distance is fundamental to the concept of spatial location and helps describe the relative positions of objects in three-dimensional space.
Here,
The apparent motion of the stars is due to the combination of the Earth's rotation on its axis and its revolution around the sun. As the Earth rotates, the stars appear to move across the sky in a west-to-east direction, and as the Earth revolves around the sun, the stars appear to move in a circular path, which is known as the apparent motion of the stars. The apparent motion of stars closer to us is greater than that of stars that are further away because of the closer proximity to Earth.
This apparent motion is also affected by the Earth's axial tilt, which causes the stars to appear to move in an elliptical path throughout the year.
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What is happening when an oxygen molecule is formed from two separate oxygen atoms?
Answers
Two from each oxygen atom. For examples of covalent bonding are water (H2O), and carbon dioxide (CO2). Covalent compounds are mostly gases or liquids with low melting points.
Atoms of two different elements must have different
A. Electrical charges
B. Number of neutrons
C. Atomic numbers
D. Energy levels
Answers
Explanation:
C. Atomic numbers....
Answer:
atomic numbers
Explanation:
In order for two atoms to be different, they have to have a different number of protons. Protons are represented by the atomic number. Thus, atoms of two DIFFERENT elements must have different atomic numbers.
I took the test and got 100%
Hope this helps!
if the ship was traveling at 5.0 knots but was 10 times more massive, how would the force of the collision on the whale compare?]
Answers
The force of the collision on the whale would be 10 times greater when the ship is 10 times more massive and traveling at 5.0 knots.
To analyze this situation, we can use the concept of momentum, which is the product of an object's mass and velocity. The momentum of the ship before the collision can be calculated using the formula:
momentum = mass × velocity
If the ship becomes 10 times more massive, its new momentum would be:
new_momentum = 10 × mass × velocity
Since the force of the collision is related to the change in momentum, we can compare the ratio of the new_momentum to the original momentum:
ratio = (10 × mass × velocity) / (mass × velocity)
The mass and velocity terms cancel out:
ratio = 10
Thus, the force of the collision on the whale would be 10 times greater when the ship is 10 times more massive and traveling at 5.0 knots.
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inclined plane how much work does it take to slide a crate 20 m along a loading dock by pulling on it with a 200-n force at an angle of 30° from the horizontal?
Answers
The work it takes to slide a crate 20 m along a loading dock by pulling on it with a 200-n force at an angle of 30° from the horizontal is 346.4J.
What is work?
The energy that is transmitted to or from an object when a force is applied along a displacement is referred to as work in physics. In its simplest form, it is typically explained as the outcome of force and displacement. Positive work is the term for the component of a force that moves the point of application when it is applied. A force is said to do negative work if, at the point of application, one of its components points in the opposite direction of the displacement.
Calculations:
Work done= component of force along displacement x displacement
= F cosΘ x d
= 200cos 30 x2
= 346.4 J
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Which of the following signals is needed to indicate that a radiation exposure has been made?
Audible sound and visible light
Density standard
Dosimetry
Atomic Number of material
Answers
The signal that is needed to indicate that a radiation exposure has been made is dosimetry. Dosimetry is the measurement and calculation of the amount of radiation to which a person or an object has been exposed, hence the correct answer is option C).
The signal that is needed to indicate that a radiation exposure has been made is dosimetry. Dosimetry is the measurement and calculation of the amount of radiation to which a person or an object has been exposed. Dosimeters are devices that are used to measure the radiation dose and provide a signal indicating the exposure level. Audible sound and visible light are not typically used to indicate radiation exposure because they do not provide accurate and quantitative information about the level of exposure. Density standard is also not a suitable signal because it is not related to radiation exposure. The atomic number of the material is not a signal that directly indicates radiation exposure. However, it is an important factor that affects the amount and type of radiation that a material can absorb or shield. The higher the atomic number of a material, the better it is at absorbing radiation. This is why lead, which has a high atomic number, is often used to shield against radiation. Therefore option C) is correct.
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A car speeds up from rest to some final velocity in some amount of time. If the time is doubled to reach the same final velocity, what
happens to the acceleration? Is this a proportional or inversely proportional relationship?
Answers
If the time is doubled to reach the same final velocity, then the acceleration will be half the acceleration before.
What is the rate of change?The rate of change of an object's velocity with respect to time is defined as acceleration. Vector quantities are accelerations.
Let's assume the final and the initial velocity of the object is v and u, respectively. Also, the time it takes is represented by t. Therefore, the acceleration can be written as,
a₁ = (v-u)/t
Now, if the time is doubled then the acceleration can be written as,
a₂ = (v-u)/2t
= (1/2) × [(v-u)/t]
= 0.5 × a₁
a₂ = 0.5a₁
Hence, If the time is doubled to reach the same final velocity, then the acceleration will be half the acceleration before.
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What is the atomic mass of N2-
Answers
Answer: 28.0134 g/mol
Explanation:
For a molecule (for example, nitrogen, N2) the mass of molecule is the sum of the atomic masses of the two nitrogen atoms. For nitrogen, the mass of the N2 molecule is simply (14.01 + 14.01) = 28.02 amu.
Quả bóng 200g chuyển động với v 4m/s đập vào tường rồi bật ra ngược chiều với cùng tốc độ độ biến thiên động lượng của quả bóng là
Answers
A magnet can move in a coil of wire to produce electricity in which system?
A. Generator
B. Motor
C. Magnet
D. Transformer
Answers
Answer:
A. Generator
Explanation:
Hope this will help
Answer:
A. Generator
Explanation:
That is the correct answer
which one of the following is a harmful software programme that can generate copies of itself and spread throughout a computer system?
a) an operating system.
b) an application system.
c) a computer virus.
d) a web log.
Answers
Since programs that copy themselves throughout a computer or network. Malware viruses piggyback on existing programs and can only be activated when a user’s opens the program.
If 2 kilograms of water is to be heated from 24.0°C to 100.0°C to make a cup of tea, how much heat must be added? (Water's specific heat is 4186 J/kg°C)A. 640 JB. 64 JC. 640,000 JD.64,000 J
Answers
Answer:
The amount of heat needed to heat 2 kilograms of water from 24.0°C to 100.0°C to make a cup of tea is (C) 640,000 J.
Explanation:
How to calculate the amount of heat needed?
The amount of heat needed can be calculated from the equationQ = m s Δ t
where Q = the amount of heat needed
m = mass of the substance being heated
s = specific heat of the substance being heated
and Δ t = the difference between the final and initial temperatures.
It is given that 2 kilograms of water are to be heated from 24.0°C to 100.0°C to make a cup of tea and the specific heat of water is 4186 J/kg°C.
Therefore,
m = 2 kgs = 4186 J/kg°CΔ t = ( 100 - 24 )°C = 76 °CPutting these values in the equation Q = m s Δ t we find,
Q = 2 x 4186 x 76 J
= 636272 J
≈ 640,000 J.
Thus the amount of heat needed to heat 2 kilograms of water from 24.0°C to 100.0°C to make a cup of tea is (C) 640,000 J.
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Rolling Stone has a circulation of 500,000 and charges \( \$ 10,000 \) for the page rate What is the CPM rate?
Answers
The CPM rate of Rolling Stone magazine is $20.
What is CPM?
In advertising, the term "cost per mille," often known as "cost per thousand," is frequently used. It represents the price an advertiser must pay for 1,000 views or impressions of their advertisement.
CPM stands for cost per mile, which is a marketing term that refers to the cost of 1,000 advertisement impressions on a web page.
Given the question, Rolling Stone has a circulation of 500,000 and charges $10,000 for the page rate.
We can determine the CPM rate by dividing the page rate by the number of impressions, then multiplying the result by 1,000.
CPM rate = (Page rate / Circulation) x 1,000
Where;
Page rate = $10,000
Circulation = 500,000
Substitute the values in the formula;
CPM rate = ($10,000 / 500,000) x 1,000
CPM rate = 0.02 x 1,000
CPM rate = $20
Therefore, the CPM rate is $20.
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Which of the following would cause the greatest increase in the entropy of an iron rod?
Holding the rod against a magnet.
Inserting the rod into molten iron
Answers
The rod into molten iron would cause the greatest increase in the entropy of an iron rod. Entropy is a measure of the disorder or randomness in a system. the rod against a magnet because the former would lead to a greater increase in randomness and disorder in the system.
This increases the disorder and randomness in the system, leading to an increase in entropy. On the other hand, holding the rod against a magnet would not cause a significant increase in entropy because the molecules in the rod would still be in a relatively ordered state. The magnetic field of the magnet would cause the electrons in the rod to align in a particular direction, but this alignment would not lead to a significant increase in disorder. In summary, inserting the rod into molten iron would cause a greater increase in entropy compared to holding the rod against a magnet because the former would lead to a greater increase in randomness and disorder in the system.
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4. The lightest pilot-driven airplane ever built was the Baby Bird. Suppose the Baby Bird moves along the ground without a pilot at a speed of 88.0 km/h. Under these circumstances, the momentum of the empty plane would be only 2,790 kg • m/s. What is the mass of the plane?
Answers
Answer:
Explanation:
mass x velocity
so i believe it'd be
2,790 x 88.0
but i could be wrong just an fyi
The most popular commercial aircraft worldwide range in weight from 30,900 to 127,000 pounds. Personal aircraft typically weigh between 740 to 2,750 pounds, which is a significant reduction in weight. The weight of a modern fighter jet ranges from 20,300 to 45,000 pounds. Aircraft are hefty.
How do you determine an airplane's weight?Determine the empty weight of the aircraft and the weights of passengers, luggage, and fuel by consulting the pilot's operating manual. To determine the moment, multiply each weight by the arm, which is the separation from the reference datum. To determine the gross weight, add up all the weights. To find the total moment, add all the moments together. The maximum weight of an aircraft is determined by the amount of lift that the wings or rotors can provide under the operational conditions for which the aircraft is designed. The maximum weight that the aircraft can safely carry is also limited by its structural strength. Empty weight (EW) is the sum of the manufacturer's 'as built' empty weight (MEW), any standard items (SI), and any operator items (OI), so EW = MEW + SI + OI. The EW is calculated for each aircraft series and each unique configuration of an aircraft and is validated by weighing it on a regular basis.To learn more about Mass of the plane refer to:
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Once you have completed a correct water cycle, include a paragraph summary of the process, and how certain steps of the process may affect you.Write your answer in the essay box below.(basically explain the water cycle keep it simple pls thx)
Answers
Answer:
water process?
Explanation:
Always wash your hands, hand washing skills. By the way you spelt thanks* improperly.
Which of the following requires the most work done by the brakes of a car?
A. slowing down from 80 mph to 55 mph
B. Stopping from 55 mph
C. equal amounts of work for both
Answers
Stopping from 55 mph requires the most work done by the brakes of a car.
Hence, the correct option is B.
When a car slows down or comes to a complete stop, the work done by the brakes is directly related to the change in kinetic energy of the car. The kinetic energy of an object is given by the equation:
Kinetic energy = (1/2) * mass * \(velocity^2\)
Comparing the options:
A. Slowing down from 80 mph to 55 mph: In this case, the car is experiencing a decrease in velocity, resulting in a decrease in kinetic energy. However, the change in kinetic energy is less compared to option B.
B. Stopping from 55 mph: In this case, the car comes to a complete stop, resulting in a significant decrease in velocity and a substantial change in kinetic energy. The brakes need to dissipate the entire kinetic energy of the car, requiring the most work.
C. Equal amounts of work for both: This option is incorrect. Slowing down from a higher speed to a lower speed (option A) requires less work than coming to a complete stop (option B). The work done by the brakes is directly proportional to the change in kinetic energy, and stopping from a higher speed involves a greater change in kinetic energy.
Therefore, Stopping from 55 mph requires the most work done by the brakes of a car.
Hence, the correct option is B.
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The basic SI unit of length is
Answers
Answer:
m
Explanation:
Metres, m, is the SI unit of length
Hope this helped you-have a good day bro cya)
What is the purpose of preheating the crucible and its cover prior to measuring its mass?
Answers
It is crucial to warm crucibles before use to lessen thermal stress on them.
Crucibles and covers are made up of porcelain that are like ceramic that contains pores in it. Any kind of water molecules from the air gets trapped in the pores of these crucible and cover.
These water molecules need to be driven out before the initial massing of the crucible and cover. The preheating helps to drive out these water molecules from the pores.
What does it mean to pre-heat a crucible?By raising the crucible’s temperature to 200°C, moisture will be removed in this step. Crucibles are protected from potential moister risk by the moister elimination procedure.
Crucibles that are brand-new or have seen a lengthy pause should be progressively heated to 200°C.
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When animals such as fox, deer and bears eat fruits from plants, the seeds are typically completely digested. True False
Answers
Answer:
False.
Explanation:
The plants rely on animals to spread their seeds, thats why they make fruits so the animals eat em, the seeds are strong enough to survive the animals stomach and come out the other end.
What is the wave speed of a wave traveling with a frequency of 37 Hz and 2 points
a wavelength of 6 m? (Remember your units!)
Answers
Answer:
222m/s
Explanation:
The speed of a wave is calculated using the forumula:
v = fλ
Lets substitute in our values:
v = 37 × 6
Which is equal to
v = 222m/s
It takes a runner 320 s to travel a final position of +1000 m at a velocity of +2.5 m/s. What was the runner's initial position
Answers
The position of the runner up traveling at a velocity of +2.5 m/s is -200 m.
What is position?Position is the location of the object (whether it's a person, a ball, or a particle) at a given moment in time.
To calculate the initial position of the runner up, we use the fomula below.
Formula:
d = vt-D.......... Equation 1Where:
d = Initial position of the runner upv = Velocity of the runner upt = TimeD = Final position of the runner upFrom the question,
Given:
v = 2.5 m/st = 320 sD = 1000 mSubstitute these values into equation 1
d = (2.5×320)-1000d = 800-1000d = -200 mThe position of the runner up is -200 m.
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For accelerated motion (the velocity is constantly changing),
the position vs time graph will be a...
A. Zero slope line
B. Unable to determine
C. Curved line
D. Constant slope line
Answers
Answer:
C
Explanation:
it means there is a change in the velocity plz mark brainliest
Can you list out the signs (positive or negative) of objective and eyepiece of microscope (simple and compund) and telescope?
NO SPAM ❌❌
Answers
For compound microscope: the objective lens produces a real, inverted image that is then magnified by the eyepiece lens to produce an upright, virtual image.
For simple microscope: The objective lens produces a real, inverted image that is viewed directly by the eye without the need for an eyepiece lens.
For telescope: The objective lens or mirror produces a real, inverted image that is then magnified by the eyepiece lens to produce an upright, virtual image. The eyepiece can be positive or negative depending on the desired magnification.
What are objective and eyepieces?The following are some signs (positive or negative) of objective and eyepiece lenses in microscopes and telescopes:
Objective lens:
Positive sign (+): used for normal, upright specimens; brings light rays to a focus in front of the lensNegative sign (-): used for inverted specimens; brings light rays to a focus behind the lensEyepiece lens:
Positive sign (+): increases the magnification of the image and produces a larger virtual imageNegative sign (-): decreases the magnification of the image and produces a smaller virtual imageLearn more about objective and eyepiece here: https://brainly.com/question/14055649
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As the distance from a charged object or particle increases, the strength of the electrical field
increases
decreases.
stays the same.
Answers
A 15.18 Kg box is at rest on a table. What is the applied force needed to just overcome the force of static friction if the coefficient of friction is 0.309? Round your answer to 2 decimal places.A 15.18 Kg box is at rest on a table. What is the applied force needed to just overcome the force of static friction if the coefficient of friction is 0.309? Round your answer to 2 decimal places.
Answers
Assuming the box is sitting on a flat surface, static friction would have a maximum magnitude of
0.309mg = 0.309 (15.18 kg) (9.80 m/s²) ≈ 45.97 N
so the applied force should have at least this magnitude.
An all female guitar septet is getting ready to go on stage. The lead guitarist, Kira,who is always in tune, plucks her low E string and the other six members, sequentially, do the same. Each member records the initial beat frequency between her low E string and Kira's low E string.
To tune an instrument using beats, more information than just the beat frequency is needed. In addition to recording the initial beat frequency , each member, except Diane, also records the change in the frequency (increase or decrease) when they increase the tension in their low E string.
Rank each member on the basis of the initial frequency of their low E string.
Rank from largest to smallest. To rank items as equivalent, overlap them.
Aiko=3Hz, fbeat increases
Chandra=1Hz fbeat decreases
Evita=5Hz fbeat decreases.
Freja=3Hz fbeat decreases.
Buffy=4Hz fbeat increases.
Expert Answer
Let f is the frequency of the Kira and \[{f_1}\] is the frequency of the Aiko.The beat frequency of Kira and Aiko is, \[{f_{{\rm{beat}}}} = \left| {…View the full answer
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Answers
Diane is not ranked because she did not record the change in frequency when increasing the tension in her low E string.
To rank the members based on the initial frequency of their low E string, we can compare the given beat frequencies. The larger the beat frequency, the larger the difference in frequency between the strings. Based on the given information, we can rank the members as follows:
Evita = 5 Hz
Buffy = 4 Hz
Aiko and Freja (tied) = 3 Hz
Chandra = 1 Hz
Note that Diane is not ranked because she did not record the change in frequency when increasing the tension in her low E string.
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