Physics College

An object whose weight is 100 lbf experiences a decrease in kinetic energy of 500 ft-lbf and an increase in potential energy of 1500 ft-lbf. The initial velocity and elevation of the object, each relative to the surface of the earth, are 40 ft/s and 30 ft, respectively.

Required:
a. Find final velocity in ft/s.
b. Find final elevation.

Answers

Answer 1

Answer:

a) the final velocity is 35.75 ft/s

b) The final elevation is 45 ft

Explanation:

Given the data in the question;

Weight of object; W = 100 lbf

Change in kinetic energy; ΔE = 500 ft-lb

[tex]\frac{1}{2}[/tex]m[tex]v_i^2[/tex] - [tex]\frac{1}{2}[/tex]m[tex]v_f^2[/tex] = ΔE

[tex]\frac{1}{2}[/tex]m[tex]v_i^2[/tex] - [tex]\frac{1}{2}[/tex]m[tex]v_f^2[/tex] = 500

multiply both sides by 2

m[tex]v_i^2[/tex] - m[tex]v_f^2[/tex] = 1000

m( [tex]v_i^2[/tex] - [tex]v_f^2[/tex] ) = 1000

[tex]v_i^2[/tex] - [tex]v_f^2[/tex] = 1000/m

[tex]v_i^2[/tex] - [tex]v_f^2[/tex] = (1000)(g) / W

we know that, acceleration due to gravity g = 9.8 m/s² = 32.18 ft/s²

so we substitute

[tex]v_i^2[/tex] - [tex]v_f^2[/tex] = (1000)(32.18) / 100

[tex]v_i^2[/tex] - [tex]v_f^2[/tex] = 32180 / 100

[tex]v_i^2[/tex] - [tex]v_f^2[/tex] = 321.8

since The initial velocity [tex]v_i[/tex] is given to be 40 ft/s;

(40)² - [tex]v_f^2[/tex] = 321.8

1600 - [tex]v_f^2[/tex] = 321.8

[tex]v_f^2[/tex] = 1600 - 321.8

[tex]v_f^2[/tex] = 1278.2

[tex]v_f[/tex] = √1278.2

[tex]v_f[/tex] = 35.75 ft/s

Therefore, the final velocity is 35.75 ft/s

we know that;

change in potential energy is;

ΔP.E = mg( h[tex]_f[/tex] - h[tex]_i[/tex] )

given that; increase in potential energy; ΔP.E = 1500 ft-lbf

and mg = Weight = 100 lbf

we substitute

1500 = 100( h[tex]_f[/tex] - h[tex]_i[/tex] )

h[tex]_f[/tex] - h[tex]_i[/tex] = 1500 / 100

h[tex]_f[/tex] - h[tex]_i[/tex] = 15 ft

given that, elevation of the object; h[tex]_i[/tex] = 30 ft

h[tex]_f[/tex] - 30 ft = 15 ft

h[tex]_f[/tex] = 15 ft + 30 ft

h[tex]_f[/tex] = 45 ft

Therefore, The final elevation is 45 ft

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Kendra wonders how she ended up with brown hair, hazel eyes, and is right handed. Using the terms amino acids, genes, proteins, and traits, explain how she ended up with these features.

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How many significant figures are in the number 54,100?

Answers

Answer:

Explanation:

The answer must be 3

The Hall effect is to be used to find the sign of charge carriers in a semiconductor sample. The probe is placed between the poles of a magnet so that magnetic field is pointed up. A current is passed through a rectangular sample placed horizontally. As current is passed through the sample in the east direction, the north side of the sample is found to be at a higher potential than the south side. Make a sketch of the situation, then decide if the number density of charge carriers is positively or negatively charged.

Answers

Answer:

the sign of these carriers is POSITIVE

Explanation:

In the effect, he found the charge carriers that were subjected to two forces, one electric and the other magnetic.

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bold indicates vectors

The electric field goes to the east, therefore the current also has this direction, the vector product of the velocity of the charge carriers towards the east and the magnetic field upwards, using the right hand rule a magnetic force is created towards the north if the carriers are positive.

In the exercise they indicate that the north side has a higher potential than the south side, therefore there must be an accumulation of carriers on this side that create an electric field (Hall) that is put to the magnetic force until reaching equilibrium when the total force is zero.

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8 A car accelerates at a rate of 10m/s
for a time of 4s and it reaches a speed of 52m/s . calculate the initial value

Answers

Answer:

From the First Law of Motion

Vf = Vi + at

"It reaches a speed of 52m/s" meaning the Final speed Vf=52

a(acceleration)=10m/s²

t=4s

Applying the formula

52=Vi + 10(4)

Vi = 52-40

Vi = 12m/s

what makes molecules move. A. covection. B. Radiation. C. Thermal or heat. D. conduction.

Answers

Radiation or Conduction?

Answer:

the answer is C

Explanation:

Four 15 Ω resistors are connected in series with a 45 V battery. What is the current in the circuit?

Answers

Answer:

Explanation:

Resistance=R=15

Voltage=45volts

we know that

[tex]\boxed{\sf Current=\dfrac{Voltage}{Resistance}}[/tex]

[tex]\\ \tt \mapsto \:Current=\dfrac{45}{15}[/tex]

[tex]\\ \tt \mapsto \:Current=\dfrac{3A}[/tex]

The current of the circuit is 0.75 amps

The first step is to write out the parameters

Four resistors of 15 in series

15+15+15+15

= 60

voltage= 45

Current= 45/60

= 0.75

Hence the current is 0.75 amps

Please see the link below for more information

https://brainly.com/question/3712069?referrer=searchResults

its un1) It is unofficial, but a strong rumor that the world will end in two years' time due to the arrival of a huge comet and its subsequent impact with Earth. You have two years to live, to get the most out of life. How would you react? What would you do? Discuss.

Answers

Answer:

I'll try my utmost best to get the most out of life...I'd do the things have always wanted to do

Sometimes it might get to me knowing fully well that in two years time the world will end but i will shake it off because the time i spend thinking about it...It will be enough to make some memories.

Hope this help anyways

1. A ford engine is provided with 80,000 W power by burning its fuel. The engine produces a kinetic energy of 96 kJ for 20 seconds before its cut out.
a. Calculate the output power by the engine in watts.
b. What is the efficiency of the engine?
c. Why is there a considerable difference in the power input and output?

Answers

Answer: a) 4800 W b) 6 % c) most of the energy of fuel is converted to heat in combustion engine

Explanation: a) Power P = W/t = 96 000 J / 20 s = 4800 W

b) efficiency η = P(putput) / P(intake) = 4800 W / 80000 W = 0,06

You throw a tennis ball straight up. Air resistance can be neglected.
(a) The maximum height above your hand that the ball reaches is H. At what speed does the ball leave your hand?
(b) What is the speed of the ball when it is a height H/2 above your hand? Express your answer as a fraction of the speed at which it left your hand.
(c) At what height above your hand is the speed of the ball half as great as when it left your hand? Express your answer in terms of H.

Answers

Answer:

(a) [tex]\sqrt{2gH}[/tex]

(b) [tex]\sqrt{gH}[/tex]

Explanation:

The maximum height = H

(a) Let the speed of the ball as it leaves the hand is u.

Use third equation of motion

[tex]v^{2}=u^{2}+2as\\0 = u^{2}- 2 gH\\u=\sqrt{2 gH}[/tex]

(b) Let the speed of the ball at H/2 is v.

Use third equation of motion

[tex]v^{2}=u^{2}+2as\\v^{2} = u^{2}- 2 g\frac{H}{2}\\v^{2}=2 g H - gH = gH\\v =\sqrt{gH}[/tex]

[tex]v^{2}=u^{2}+2as\\\frac{u^{2}}{4} = u^{2}- 2 gh \\\\2 g h = \frac{3u^{2}}{4}\\h =\frac{3u^{2}}{8g}[/tex]

How do you make a mirages?

Answers

Answer: when the ground is very hot and the air is cool. The hot ground warms a layer of air just above the ground. When the light moves through the cold air and into the layer of hot air it is refracted (bent). A layer of very warm air near the ground refracts the light from the sky nearly into a U-shaped bend.

Explanation:

NEED HELP PLZ!!! ASAP

Which of the following happens during a solar eclipse?

The moon appears red.
The moon casts a shadow on Earth.
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Earth comes between the sun and the moon.

Ok so I'm Confused, that last answer- Shouldnt that say the moon comes between the sun and the earth? This is what it says on my test instead..

Answers

U r correct mate it's the right answer.

Hope it helps u

Plz mark me brainlest

सत्मार्ग र शान्तिले नै समाजलाई सभ्य बनाउँछ भन्ने विषयमा ५० शब्दसम्मको एउटा अनुच्छेद
लेख्नुहोस्।

Answers

Answer:

So you have a question

Explanation:

either way have a nice day

a 60 kg pupil runs for 600m in 1 minute uniformly calculate kinetic energy

Answers

velocity = traveled distance ÷ time of the traveled distance is seconds

velocity = 600 ÷ 60

velocity = 10 m/s

_________________________________

Kinetic Energy = 1/2 × mass × ( velocity )^2

KE = 1/2 × 60 × ( 10 )^2

KE = 30 × 100

KE = 3000 j

A vehicle reaches a speed of 7.5 m/s over 15 seconds. What is its acceleration if it
starts from rest?
a. -0.5 m/s2
b. 0.5 m/s?
c. 2 m/s?
d. 22.5 m/s2

Answers

[tex]acceleration = \frac{velocity}{time} = \frac{7.5}{15} = 0.5ms^-^2[/tex]

So the answer is option b.

In a chemical reaction, substances react in a specific ratio. Chemical reactions are used to make many products, including food. For a company that carries out a chemical reaction to make a product, why would it be important to know the ratio of substances?

Answers

Answer: “Chemical equations need to be balanced in order to satisfy the law of conservation of matter, which states that in a closed system matter is neither created nor destroyed. There are some things called mole ratios, which are important because mole ratios allow you change moles of a substance to moles of another substance. The mole ratio is the magic that changes from A to B. The mole ratios come from the chemical formula or equation.”

You need to make sure you have an equal balance so that you don’t make a mistake and mess up the reaction. If anything goes minutely wrong, it may alter the substance. Knowing the ratios of substances can help to make the product as expected.

It is important to know the ratio of substances because:

Mole ratios are important because mole ratios allow you change moles of a substance to moles of another substance. The mole ratio is the magic that changes from A to B. The mole ratios come from the chemical formula or equation.The mole ratios are determined using the coefficients of the substances in the balanced chemical equation. Mole ratios are used as a means of comparison of substances in a balanced chemical equation in order to determine amounts.

Example: 2H₂ + O₂ → 2 H₂O

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brainly.com/question/14197404

1. A 2,000-turn solenoid is 65 cm long and has cross-sectional area 30 cm2. What rate of change of current will produce a 600 Volts emf in this solenoid.

Answers

Answer:

[tex]\frac{dI}{dt} = 2.59\ x\ 10^4\ A/s[/tex]

Explanation:

First, we will calculate the inductance of the solenoid by using the following formula:

[tex]L = \frac{\mu_o AN^2}{l}[/tex]

where,

L = self-inductance of solenoid = ?

μ₀ = permeability of free space = 4π x 10⁻⁷ N/A²

A = Cross-sectional area = 30 cm² = 3 x 10⁻³ m²

N = No. of turns = 2000

l = length = 65 cm = 0.65 m

Therefore,

[tex]L = \frac{(4\pi\ x\ 10^{-7}\ N/A^2)(3\ x\ 10^{-3}\ m^2)(2000)^2}{0.65\ m}\\\\L = 0.0232\ H[/tex]

Now, we will use Faraday's law to calculate the rate of change of current:

[tex]emf = L\frac{dI}{dt}\\\\ \frac{dI}{dt} =\frac{emf}{L} \\\\ \frac{dI}{dt} =\frac{600\ V}{0.0232\ H}\\\\ \frac{dI}{dt} = 2.59\ x\ 10^4\ A/s[/tex]

The take-up reel of a cassette tape has a radius of 2.5 cm. Find the length of the tape that passes around the reel in 7.1 s when the reel rotates at an average angular speed of 1.9 rad/s.

Answers

Answer:

s = 0.337 m

Explanation:

First, we will find the angular displacement of the reel:

[tex]\theta = \omega t[/tex]

where,

θ = angular displacement = ?

ω = angular speed = 1.9 rad/s

t = time taken = 7.1 s

Therefore,

θ = (1.9\ rad/s)(7.1 s)

θ = 13.5 rad

Now, we will find out the length of tape:

s = rθ

where,

s = length of tape = ?

r = radius of reel = 2.5 cm = 0.025 m

Therefore,

s = (0.025 m)(13.5 rad)

s = 0.337 m

if 36C ofcharge pass through a write in 4s current is it carrying?

Answers

Answer:

The current flowing through the wire is 9 A.

Explanation:

Given;

quantity of charge passing through the wire, Q = 36 C

duration of the charge flow, t = 4 s

The current flowing through the wire is calculated as;

Q = It

I = Q / t

where;

I is the current flowing in the wire

I = 36/4

I = 9 A

Therefore, the current flowing through the wire is 9 A.

how are force and motion related

Answers

Force is used to put things in motion you can’t have motion without force!
Even if it just pushing a piece of paper you still use force to put the paper in motion!

A 100-turn, 7.0-cm-diameter coil is made of 0.50-mm-diameter copper wire. A magnetic field is perpendicular to the coil. At what rate must B increase to induce a 2.0 A current in the coil?

Answers

Answer:

The rate of increase of the magnetic field is 0.0311 T/s.

Explanation:

Given;

number of turns of the coil, N = 100 turn

diameter of the coil, D = 7.0 cm = 0.07 m

diameter of the copper wire, d = 0.5 mm = 0.5 x 10⁻³ m

induced current, I = 2.0 A

The induced emf is calculated as;

[tex]emf = IR = NA\frac{dB}{dt}\\\\\frac{dB}{dt} = \frac{IR}{NA} \\\\Where; A \ is \ area \ of \ the \ coil = \frac{\pi D^2}{4}\\\\[/tex]

[tex]\frac{dB}{dt}[/tex] is the rate of increase of the magnetic field, B

R is the resistance of the copper wire

[tex]R = \frac{\rho L}{A} = \frac{\rho D}{A}= \frac{\rho D}{\frac{\pi d^2}{4} }[/tex]

Where; ρ is the resistivity of copper wire = 1.68 x 10⁻⁸ Ωm

[tex]R = \frac{(1.68 \times 10^{-8})(0.07)}{\frac{\pi (0.5\times 10^{-3})^2}{4} } \\\\R = 5.989 \times 10^{-3} \ ohms[/tex]

[tex]\frac{dB}{dt} = \frac{(2)(5.989 \times 10^{-3})}{(100)(\frac{\pi \times (0.07)^2}{4} )} \\\\\frac{dB}{dt} =0.0311 \ T/s[/tex]

Therefore, the rate of increase of the magnetic field is 0.0311 T/s.

. Two identical vehicles traveling at the same speed are made to collide with barriers in an insurance company collision test. The first vehicle collides with a concrete barrier, and stops in a time of approximately 0.1 s. The second vehicle collides with a collapsible barrier, and comes to rest in about 1 second. Which object is subject to a larger force

Answers

Answer:

F₁ / F₂ = 10

therefore the first out is 10 times greater than the second barrier

Explanation:

For this exercise let's use the relationship between momentum and momentum.

I = F t = Δp

in this case the final velocity is zero

F t = 0 -m v₀

F = m v₀ / t

in order to answer the question we must assume that the two vehicles have the same mass and speed

concrete barrier

F₁ = -p₀ / 0.1

F₁ = - 10 p₀

barrier collapses

F₂ = -p₀ / 1

let's look for the relationship of the forces

F₁ / F₂ = 10

therefore the first out is 10 times greater than the second barrier

If unlike magnetic poles attract, how does a magnet attract an un-magnetized piece of metal such as a piece of iron?
A
It does this via a process called magnetic induction which temporarily makes a magnet of the metal.

B
It can only do this if the piece of metal already is a magnet internally.

C
What actually happens is that the un-magnetized metal attracts the magnet rather than the other way around.

D
Only powerful electro-magnets, such as are found in wrecking yards, can attract unmagnetized metals.

Answers

Answer:

Explanation:

The lets say the magnet is is facing the north and a piece of iron is near it. The iron will become magnetized since the protons will be repelled leaving only the electrons creating a magnetic field. Or in other words a temporary magnet is made, this is only as long a the actual magnet is close enough to the iron.

If a team of workers comes to a consensus, what probably happened in the meeting?
A. They compromised with each other to reach an agreement.
B. They disagreed and were unable to come to a decision.
OC. They were forced by their manager to follow a new policy.
O D. They all turned in their letters of resignation.

Answers

Answer:

Explanation:

A consensus is when you come to an agreement

When we experience positive "g forces", it is as if we have become...

Answers

Answer:

heavier

Explanation:

Draw Aufbua diagram of sodium ion

Answers

Answer:

Aufbau diagram of sodium ion:

2s²,2p⁶,3s¹

Cora’s doctor suspects that she has acid reflux. He prescribes
for her.

Answers

Answer: antacids

Explanation: Excess acid secretion in the stomach often causes nausea, chest pain, and leaves a bitter taste in the mouth. Doctors perscribe antacids to neutralize the acid.

Answer: antacids

Explanation: Excess acid secretion in the stomach often causes nausea, chest pain, and leaves a bitter taste in the mouth. Doctors perscribe antacids to neutralize the acid.

“Is it true or wrong to say that an automobile at rest can be accelerating very fast? Either yes or no explain it with mathematical background

Answers

Answer:

Yes.

a = dv/dt

but v might be zero in an instant.

Take the example of a pendulum.

Acceleration is defined as the rate of change of the velocity of the body. Yes, an automobile at rest can accelerate very fast.

What is acceleration?

Acceleration is defined as the rate of change of the velocity of the body. Its unit is m/sec².It is a vector quantity. It requires both magnitudes as well as direction to define.

[tex]\rm a=\frac{dv}{dt}[/tex]

a is the acceleration of the body

dv is the change of velocity of the body

dt is the change in the time interval

The acceleration is defined as the change in velocity, and the slope of velocity is found as acceleration. It can be said that the body is at rest its velocity is zero.

The acceleration of the body can be increased when the body changes its direction. So the moment at which the body changes the direction the body is at rest after that the body can accelerate.

To learn more about acceleration refer to the link;

https://brainly.com/question/969842

g You shine orange laser light that has a wavelength of 600 nm through a narrow slit. The slit forms a diffraction pattern on a distant screen that has been set up behind the slit. The first dark fringe in the diffraction pattern is 4.0 cm from the center point of the pattern. If you replace the orange laser with an unknown laser and observe that the second dark fringe of the diffraction pattern appear at 4.0 cm from the center point, what is the wavelength of the unknown laser

Answers

Answer:

λ = 3 10⁻⁷ m, UV laser

Explanation:

The diffraction phenomenon is described by the expression

a sin θ = m λ

let's use trigonometry

tan θ = y / L

as in this phenomenon the angles are small

tan θ = [tex]\frac{sin \ \theta}{cos \ \theta}[/tex] = sin θ

sin θ = y / L

we substitute

a y / L = m λ

let's apply this equation to the initial data

a 0.04 / L = 1 600 10⁻⁹

a / L = 1.5 10⁻⁵

now they tell us that we change the laser and we have y = 0.04 m for m = 2

a 0.04 / L = 2 λ

a / L = 50 λ

we solve the two expression is

1.5 10⁻⁵ = 50 λ

λ = 1.5 10⁻⁵ / 50

λ = 3 10⁻⁷ m

UV laser

What would happen if I removed the battery from the circuit?

Answers

Answer:

The current would stop

Explanation:

Electric currents are interesting because they carry little to no momentum. As soon as you remove a power source, the whole current halts.

Volcanic process refers to the eruptive and noneruptive activities that occur on a volcano. Volcanic activities usually
results if one of the following happens: A). Deep within the core of the Earth, it is so hot that some rocks melt and
become a thick and sticky substance called (16)_
Magma B) This substance gets hotter and hotter and pressure
builds deep in the (17)
of the volcano. C) Eventually, magma will push up toward the surface of the
Earth through the volcano's crater and escape through vents in the earth. D) When magma erupts from the volcano, it is
called (18)
During an eruption, volcanic asin and ouiet rock pa licies called (19)
alsu escape
violently into the air and can cause major damage to the volcano's surrounding environment. E) (20)
that erupts from the volcano will fall back down onto the Earth like powdery snow that can cover and suffocate
anlants and animals and also contaminate streams and rivers.

Answers

I need help too anyone know

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