Complete Question
A sled of mass m is coasting at a constant velocity on the ice covered surface of a lake. Three birds, with a combined mass 0.5m, gently land at the same time on the sled. The sled and birds continue sliding along the original direction of motion. How does the kinetic energy of the sled and birds compare with the initial kinetic energy of the sled before the birds landed?
a) The final kinetic energy is one half of the initial kinetic energy.
b) The final kinetic energy is one third of the initial kinetic energy.
c) The final kinetic energy is one quarter of the initial kinetic energy.
d) The final kinetic energy is one ninth of the initial kinetic energy.
e) The final kinetic energy is equal to the initial kinetic energy
Answer:
The correct option is b
Explanation:
From the question we are told that
The mass of the sled is m
The mass of the three birds is [tex]m_b = 0.5 m[/tex]
Generally from the law of momentum conservation,
The initial momentum of the boat = final momentum of the boat
Hence
[tex]m * v = (m_b+ m) * v_2[/tex]
=> [tex]m v = (0.5m+ m) * v_2[/tex]
=> [tex]m v = 1.5m* v_2[/tex]
Here v is the velocity of the boat before the birds landed and [tex]v_2[/tex] is the velocity after the birds landed
So
[tex]v_2 = \frac{2}{3} v[/tex]
Generally the initial velocity of the boat before the birds landed is mathematically represented as
[tex]K_i = \frac{1}{2} * m * v ^2[/tex]
Generally the final velocity of the boat when the birds have landed is mathematically represented as
[tex]K_f = \frac{1}{2} * (m_b + m ) * v_2^2[/tex]
=> [tex]K_f = \frac{1}{2} * (0.5m + m ) * (\frac{2}{3} v)^2[/tex]
=> [tex]K_f = \frac{1}{2} * 1.5m * (\frac{2}{3} v)^2[/tex]
=> [tex]K_f = \frac{1}{2} * 1.5m * \frac{4}{9} v^2[/tex]
=> [tex]K_f = \frac{1}{2}m v^2 * \frac{1}{3}[/tex]
Comparing this equation with that of the initial kinetic energy
=> [tex]K_f = \frac{1}{3} K_i[/tex]
The kinetic energy of the sled and birds is one-third the initial kinetic energy of the sled before the birds landed.
What is kinetic energy?When an object is in motion, then the energy possessed by the object at the state of motion is known as its kinetic energy.
Given data -
The combined mass of three birds is, M = 0.5m.
Let m be the mass of the sled. Then applying the conservation of linear momentum as,
The initial momentum of the boat = final momentum of the boat
mv = (M + m)v'
v is the velocity of the boat before the birds landed and v' is the velocity after the birds landed.
mv = (0.5m + m)v'
mv = 1.5mv'
v = 3/2 v'
or
v' =2/3v
The initial kinetic energy of the boat before the birds landed is mathematically represented as
[tex]K_{1}= \dfrac{1}{2}mv^{2}[/tex]
And the final kinetic energy of the boat when the birds have landed is mathematically represented as,
[tex]K_{2}=\dfrac{1}{2}(M+m)v'^{2}\\\\K_{2}=\dfrac{1}{2}(1.5m) \times 4/9v^{2}\\\\K_{2}=\dfrac{1}{3} \times \dfrac{1}{2}mv^{2}\\\\K_{2}=\dfrac{1}{3} \times K_{1}[/tex]
Thus, we can conclude that the kinetic energy of the sled and birds is one-third the initial kinetic energy of the sled before the birds landed.
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An unbalanced force of 23 N is applied to a 13 kg mass. What is the acceleration of the
mass?
Answer:
1.77 m/s^2
Explanation:
since it is unbalanced there must be net force(resultant force)
[tex]net \: force \: = accleration \: \times mass[/tex]
net force = 23N
mass = 13kg
a = x
x = 23/13
= 1.769...
approximately = 1.77 m/s^2
Click to review the online content. Then answer the question(s) below, using complete sentences. Scroll down to view additional questions.
Online Content: Site 1
How do wetlands reduce flooding and erosion? (Site 1)
Answer:
Wetlands reduce flooding and erosion by filtering water.
Explanation:
Answer:
Wetlands reduce flooding and erosion by filtering water.
Explanation:
When there are equal forces from opposite directions acting on an object, the forces are said to be which of the following? (4 points)
A.Positive
B.Negative
C.Balanced
D.Gravitational
Answer: C. Balanced
Explanation:
I took the test and got it right.
Your are part of a team to help design the atrium of a new building.Your boss, the manager of the project, wants to suspend a 6.2 kg sculpture high over the room by hanging it from the ceiling using thin, clear fishing line (string) so that it will be difficult to see how the sculpture is held up. The only place to fasten the fishing line is to a wooden beam which runs around the edge of the room at the ceiling.The fishing line that she wants to use will hold 10 kg so she suggests attaching two lines to the sculpture to be safe. Each line would come from the opposite side of the ceiling to attach to the hanging sculpture. Her initial design has the first line making an angle of 12.67∘with the ceiling and the second line making an angle of 16.15∘ with the ceiling. She knows you took physics, so she asks you if her design can work.
How much force would the first line exert on the beam holding it up?
Assume that g=9.8 m/s−2.
Answer:
The answer is below
Explanation:
Given that the mass of the sculpture (m) = 6.2 kg, [tex]\theta_1=12.67^o,\theta_2=16.15^o[/tex]
[tex]Sum\ of\ horizontal\ force\ is\ zero\ hence:\\\\T_1cos(\theta_1)=T_2cos(\theta_2)\\\\T_1=\frac{T_2cos(\theta_2)}{cos(\theta_1)}\\ \\Sum\ of\ vertical\ force\ is\ zero:\\\\T_1sin(\theta_1)+T_2sin(\theta_2)=mg\\\\\frac{T_2cos(\theta_2)}{cos(\theta_1)}sin(\theta_1)+T_2sin(\theta_2)=mg\\\\T_2=\frac{mg}{\frac{cos(\theta_2)}{cos(\theta_1)}sin(\theta_1)+sin\theta_2} \\\\T_2=\frac{6.2*9.81}{\frac{cos(16.15)}{cos(12.67)}sin(12.67)+sin16.15} =123.1\ N\\\\[/tex]
[tex]T_1=\frac{T_2cos(\theta_2)}{cos(\theta_1)}=121.2\ N[/tex]
One end of a horizontal string is attached to a vibrating blade, and the other end passes over a pulley as in Figure (a). A sphere of mass 1.00 kg hangs on the end of the string. The string is vibrating in its second harmonic. A container of water is raised under the sphere so that the sphere is completely submerged. In this configuration, the string vibrates in its second harmonic (or the third normal mode of oscillation) as shown in Figure (b). What is the radius of the sphere?
Answer:
when it weighs 2kg it is 7.38
Explanation:
hope this helps
Occupants of cars hit from behind, even at low speed, often suffer serious neck injury from whiplash. During a low‑spee rear‑end collision, a person's head suddenly pivots about the base of the neck through a 50∘ angle, a motion that lasts 220 ms.The distance from the base of the neck to the center of the head is typically about 20 cm, and the head normally comprises about 6.0% of body weight.Model the motion of the head as having a uniform speed over the course of its pivot. Compute answers to two significant figures.1. What is the acceleration ????centacent of the head during the collision?2. What force ????F does the neck exert on the head of a 65 kg65 kg person in the collision? Neglect the force of gravity on the head, and report the answer in units of both newtons and pounds.3. Would headrests mounted to the backs of the car seats help protect against whiplash? Why or why not?a. Yes. A headrest applies an upward force on the head, along the direction of the neck, that cancels the downward force applied by the neck.b. Yes. A headrest ensures that both the head and the body experience the same forward force at roughly the same time.c. No. A headrest applies a mostly horizontal force to the head, so does not affect the mostly vertical force applied by the neck during whiplash.d. No. A headrest reduces the angle traversed by the head, not the speed of the head relative to the body, thus it does not affect the force that the neck applies to the head.
Answer:
a) a= 19 m/s2, b ) F = F = 38 N
c) the correct one is B
Explanation:
1) To solve this exercise, let's use the concept of torque, let's start by looking for the mass of the mass of the head, which is 65 of 65 kg
m= 0.06 65 = 3.9 kg
torque is defined
τ = F x R
the bold indicate vectors
τ = F R sin θ
the force is the weight of the head and the distance R = 0.20 m
τ = mg R sin θ
τ = 3.9 9.8 0.2 sin 50
τ = 5.86 N m
Newton's second law expression for rotational motion is
τ = I α
In general, the head is approximated by a sphere, so the moment of foolishness with respect to the base of the neck (turning point) using the parallel axis theorem is
I = I_sphere + m d²
Neck height data is not indicated, so we will assume that it is zero (d = 0)
I = 2/5 m R²
angular and linear acceleration are related
a = α R
α = a / R
let's replace
τ = 2/5 mR² (a / R)
a = 5/2 τ / mR
let's calculate
a = 5/2 5.86 / (3.9 0.2)
a = 18.8 m / s²
a= 19 m/s²
2) as the neck and the head are related, the forces are action and reaction, therefore the neck force is
F = m g
F = 3.9 9.8 = 38.2 N
F = 38 N
3) He asks us about the efficiency of the headrest, after reviewing the different alternatives, the correct one is B
Yes. A headrest ensures that both the head and the body experience the same forward force at approximately the same time.
The nervous system has two distinct branches. They are the:
Answer:
central nervous system
peripheral nervous system
Explanation:
The nervous system has two main parts: The central nervous system is made up of the brain and spinal cord. The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.Oct 1, 2018
Answer:
The central nervous system
The peripheral nervous system
Explanation:
The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is everything else
how does 'g' at a point vary with the distance from the centre of earth?
Answer:
No gravity
Explanation:
because their is not gravity on earth and also close to the sun but not as close as mecury
w
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2. Identify the correct statement about the diagrams above.
O Y represents a mixture and Z represents an element.
O Y represents an compund and X represents a pure substance.
O X represents a mixture and W represents a pure substance
O W represents an element and Y represents a mixture.
Answer: W represents an element Y represents a mixture
Explanation: I just took a quiz on this and got it right. Good Luck
What is the final velocity if you have an initial velocity of 4 m/s with an acceleration of 2 m/s2 over 5 second interval interval
Answer:
14m/s
Explanation:
A ball is thrown horizontally from a 12 m
building with a speed of 2.0 m/s.
-high
How far from the base of the building does the ball hit the ground ?
Answer:
24
Explanation:
you multiply 2.0x12
A car traveling east in a straight line on a highway decreases its speed from 30. meters per second to 23. meters per second in 2.0 seconds. What is the magnitude of the car's average acceleration to the nearest tenths place, during this time interval?
Answer:
Acceleration = -3.5 m/s²
Explanation:
Given:
Initial velocity u = 30 m/s
final velocity velocity v = 23 m/s
Time t = 2 second
Find:
Acceleration
Computation:
v = u + at
23 = 30 + (a)(2)
-7 = 2 a
a = -7 / 2
a = -3.5 m/s²
Acceleration = -3.5 m/s²
an airplane travels down a Runway at 1500 m in 17s what is the average speed
Answer:
88.23 m/s
Explanation: The equation for speed is s=d/t so in other words, speed equals distance over time so the distance is 1500 and the time is 17 seconds so you just devide 1500 by 17 and you get the speed. Remember to include your unit m/s after your answer
In which scenario will the two objects have the greatest gravitational force
between them?
A. Mass of object 1 = 22 kg
Mass of object 2 = 14 kg
Distance between objects = 28 m
B. Mass of object 1 = 22 kg
Mass of object 2 = 16 kg
Distance between objects = 48 m
C. Mass of object 1 = 22 kg
Mass of object 2 = 14 kg
Distance between objects = 48 m
D. Mass of object 1 = 22 kg
Mass of object 2 = 16 kg
Distance between objects = 28 m
Answer: The answer is D
Explanation:
The greater the mass and the less the distance
The two objects that will have the greatest gravitational force between them is:
D. Mass of object 1 = 22 kg
Mass of object 2 = 16 kg
Distance between objects = 28 m
What is Gravitational force?It is an appealing power that exists between all items with mass; an article with mass draws in one more particle with mass; the size of the power is straightforwardly corresponding to the majority of the two articles and contrarily relative to the square of the distance between the two particles.
It is given by:
[tex]F=G*\frac{m_1*m_2}{r^2}[/tex]
So, for the highest value of gravitational force there must be greater mass and lesser distance. So the option that holds good is option D.
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The cheetah, the fastest land animal, can sprint at 30 m/s. Could the cheetah get a speeding
ticket on a highway where the speed limit is 55 mph?
Answer:
#1, cheetas can't go 30 miles per second. #2 no
Explanation:
No because animals can't get tickets.
Answer:
yes
Explanation:
it would be going 67.108 mph,
4. A 65 kg woman is inside an elevator. Calculate her apparent weight (Normal Force) for the following cases:
a. The elevator moves at constant speed of 10 m/s downward (2 pts)
b. The elevator accelerates upward at a constant rate of 2.4 m/s2 (2 pts)
c. If the scale read 450 N. Find the magnitude and direction of the elevator’s acceleration. (3 pts)
Answer:
Explanation:
a ) Let her apparent weight be W₁
Net force on her = W₁ - mg
acceleration a = 0
W₁ - mg = 0
W₁ = mg = 65 x 9.8 = 637 N
b )
a = 2.4 m /s²
W₁ - mg = ma
W₁ = m(g + a )
= 65 x ( 9.8 + 2.4 )
= 793 N
c )
W₁ = 450 N
a = ?
W₁ - mg = ma
450 - 65 x 9.8 = 65 x a
65 a = - 187
a = - 2.87 m /s²
acceleration is negative therefore , it must be downwards .
The elevator was accelerating downward at a constant rate of -3.1 m/s²
Let the acceleration due to gravity (g) = 10 m/s²
a) When moving at constant speed of 10 m/s downward:
Net force = mass * g = 65 kg * 10 m/s² = 650N
b) Net force = Mass * g + mass * acceleration
Net force = (65 * 10) + (65 * 2.4) = 806 N
c) Net force = Mass * g + mass * acceleration
450 = 65 * 10 + (65*a)
65a = -200
a = -3.1 m/s²
The elevator was accelerating downward at a constant rate of -3.1 m/s²
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I am so close to wanting to drop out of physics
I'm in college and idk why physics has to be this tough. I took physics back in high school, and it was super easy & I had a really nice teacher.
But now that I'm in college, my professor does no help and literally 60 people dropped out of his class bc his class is hard. I am going to fail my midterm this week. idk what to do and Im sick and tired but its a requirement.
I literally wanna drop out of college bc of physics
Answer: Dont drop out i know school can be a headache but if you try you can accomplished anything.
Explanation:
Answer:
college vs high school.
Explanation:
hello! first, i see the comparison between college and highschool. remember that college professors are much more strict. they dont give participation awards or guide you. this is the time to push yourself! your so close to your goal, why give up from one class? you got this! every question you get wrong or right is a step closer to understanding it better. dont give up. i hope i could help!
To describe a position in more than one
dimension, you must use more than one______
Answer:
To describe a position in more than one dimension you must use more than one reference point. The reference point is a basis for evaluation, assessment or comparison; a criterion.
Explanation:
Hope this answer help :D
Answer:
reference point
Explanation:
In what climates would you expect soil to form fastest? Why?
Answer:
Soils develop faster in warm, moist climates and slowest in cold or arid ones. Rainfall is one of the most important climate factors in soil formation.
Please mark me brainliest!
Hope this helped God bless :)
Soil formation occurs more swiftly in warm, humid areas than it does in cold or arid ones.One of the most crucial climatic variables for the formation of soil is rainfall. The breakdown of large soil particles into smaller ones is accelerated by creatures such as bacteria, plants, and animals.
What climates soil to form fastest?The rate of chemical reactions is accelerated by rising temperature, which also accelerates soil formation. Faster plant and bacterial growth in warmer climates aids in the weathering of materials and the formation of soils.
The formation of soil is another indirect effect of climate on organisms. Weathering is accelerated by precipitation and warm temperatures, which increases the amount of soil development. Rainfall increases the amount of organic matter, lowers pH, accelerates the leaching of basic ions, moves mud, etc.
Therefore, In warm, wet regions, soil development happens more quickly than in cold or arid ones. One of the most crucial climatic variables for the formation of soil is rainfall.
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If a pair of shoes weighs 0.3 N on Pluto what is the strength of gravity on Pluto
Answer:
0.6 m/s 2
Explanation:
It takes 25.7 N to push a crate
at a constant speed across flat
ground where uk
= 0.238.
What is the normal force acting
on the crate?
(Unit = N)
Answer:
108 N
Explanation:
Divide the force by uk to get the normal force
(25.7)/(0.238) = 107.98 N = 108 N
Answer:
107
Explanation:
how is the process of finding the mass of a gas different from that of finding the mass of a liquid why is the difference necessary
Object has a mass of 35g and a density of 5g/cm3.
What is the volume? *
Answer:
The answer is 7.0 mLExplanation:
The volume of a substance when given the density and mass can be found by using the formula
[tex]volume = \frac{mass}{density} \\[/tex]
From the question
mass = 35 g
volume = 5 g/cm³
We have
[tex]volume = \frac{35}{5} \\ [/tex]
We have the final answer as
7.0 mLHope this helps you
What is the acceleration of the object if a 300-N force acting on a 25 kg object
Given parameters:
Force on the object = 300N
Mass of object = 25kg
Unknown:
Acceleration = ?
Solution:
According to Newton's second law of motion, force is a product of mass and acceleration.
Force = mass x acceleration
Input the parameters and solve for the acceleration;
300 = 25 x acceleration
Acceleration = 12m/s²
The acceleration is 12m/s²
Imagine that you throw a rock into the air. When you release the rock, it is moving at 19.4 m/s. The rock flies straight up into the air and returns back to your hand. For how long was the rock in the air? Note: acceleration due to gravity is -9.81 m/s/s.
Answer:
4 s
Explanation:
The following data were obtained from the question:
Initial velocity (u) = 19.4 m/s.
Acceleration due to gravity (g) = –9.81 m/s²
Total time (T) =.?
Next, we shall determine the time take by the rock to get to the maximum height. This can be obtained as follow:
NOTE: At maximum height, the final velocity is zero.
Initial velocity (u) = 19.4 m/s.
Acceleration due to gravity (g) = –9.81 m/s²
Final velocity (v) = 0 m/s
Time taken to reach the maximum height (t) =.?
v = u + gt
0 = 19.4 + (–9.81 × t)
0 = 19.4 – 9.81t
Collect like terms
0 – 19.4 = –9.81t
–19.4 = –9.81t
Divide both side by –9.81
t = –19.4 / –9.81
t ≈ 2 s
Thus, it took approximately 2 s for the rock to reach its maximum height.
Finally, we shall determine the total time spent by the rock in the air as follow:
Time taken to reach the maximum height (t) = 2 s
Total time spent in air (T) =?
The total time (T) spent by the rock in the air will be two times the time taken (t) to reach the maximum height i.e
T = 2t
t = 2 s
T = 2 × 2
T = 4 s
Therefore, the rock spent approximately 4 s in the air.
2.What is the weight of an object that has a mass of 5 kg?
Answer:
5 kg
or 11 lbs
Explanation:
A planned high-speed train between Houston and Dallas will travel a distance of 386 kilometers in 5.40 × 103 seconds. What is the average speed of this train?
A shell is fired from a mortar over level terrain. The firing speed is 59 m/s and the mortar is aimed 70° above the horizontal. Find the range of the shell.
Answer:
228.23m
Explanation:
Vy=59sin70=55.44m/s
x=V0t+1/2at^2
0=55.44t-4.9t^2
t=11.31s
Vx=59cos70=20.18m/s
Range=20.18*11.31=228.23m
Velocity is the
i. distance travelled per unit time
il. time taken per unit distance
a.
9.
ii. time taken per unit displacement
iv. displacement per unit time
Okay, hun. Velocity is a vector quantity that measures displacement over a period of time. Velocity = Speed/Time (v=s/t). Hope this helped you. I took physics over 4 years ago. I'm more of a biology/chemistry person. (I major in those)
What are four metals other than iron that can be made to exhibit magnetic properties? Fill in the blank. Every magnet has _______ unlike poles. The _______ within a magnet lies between the north and south poles. If the north pole of a bar magnet is brought near the _______ pole of another magnet, the two magnets will repel one another. A material that’s attracted by a magnet but doesn’t necessarily become a magnet itself is called a/an _______ material.
Answer:
Four metals other than iron that can be made to exhibit magnetic properties are nickel, cobalt, manganese, and chromium.
two
neutral region
north
magnetic
Explanation:
PennFoster
The four metals other than iron that can be made to exhibit magnetic properties are:
NickelCobaltManganeseChromium.
Furthermore, the words which can be used to accurately complete the sentences below are:
Two Neutral region North MagneticThe magnet has two unlike poles and in the neutral region, there is the South and North poles.
The North and South poles repel each other and a magnet can attract any material which contains iron materials.
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