Answer:
Crumple zones are designed to absorb and redistribute the force of a collision. ... Also known as a crush zone, crumple zones are areas of a vehicle that are designed to deform and crumple in a collision. This absorbs some of the energy of the impact, preventing it from being transmitted to the occupants.
Robin fired a bullet of mass 100 gm from a gun of mass 5 kg. The bullet leaves the gun with a speed of 400 m/s. After penetrating 4 cm of a plank of 10 cm, the bullet loses one third of its initial velocity.
a. Calculate the backward velocity of the gun?
b. Can the bullet penetrate the plank of the wood completely? Explain mathematically.
please help
(a) The recoil or backward velocity of the gun is 8 m/s.
(b) The bullet cannot penetrate the plank of the wood completely.
The given parameters include;
mass of the bullet, m₁ = 100 g = 0.1 kgmass of the gun, m₂ = 5 kginitial velocity of the bullet, u₁ = 400 m/sthickness of the plank, x = 10 cm(a) The backward or recoil velocity of the gun is calculated by applying the principle of conservation of linear momentum.
let the backward or recoil velocity of the gun = u₂m₁u₁ + m₂u₂ = 0
m₂u₂ = -m₁u₁
[tex]u_2 = -\frac{m_1u_1}{m_2} \\\\u_2 = - \frac{0.1 \times 400}{5} \\\\u_2 = -8 \ m/s[/tex]
Thus, the recoil or backward velocity of the gun is 8 m/s.
(b) determine if the bullet can penetrate the plank of the wood completely
the bullet traveled 4 cm and lost ¹/₃ of u₁the remaining distance to completely penetrate the plank = 6 cmthe final velocity of the bullet at 4 cm, v = 400 - ¹/₃ x 400 m/s = 266.67 m/sthe acceleration of the bullet is calculated as;
v² = u₁² + 2as
2as = v² - u²
[tex]a = \frac{v^2 -u_1^2}{2s} \\\\a = \frac{(266.67)^2 -(400)^2}{2\times 0.04} = -1.111 \times 10^6 \ m/s^2[/tex]
Finally, determine the distance traveled by the bullet when it comes to a complete stop, that is the final velocity = 0
[tex]v_f^2 = v^2 + 2ad\\\\2ad = v_f^2 - v^2\\\\d = \frac{v_f^2 - v^2}{2a} \\\\d = \frac{(0) - (266.67)^2}{2(-1.111\times 10^6)} \\\\d = 0.032 \ m[/tex]
d = 3.2 cm
The total distance traveled by the bullet inside the plank = 4 cm + 3.2 cm = 7.2 cm
Therefore, the bullet cannot penetrate the plank completely.
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a busis moving with the initial velocity 10m/s . after 4 seconds, the velocity becomes 30m/s . find the acceleration produce by bus,......please I need help
Answer:
5 m/s²
Explanation:
Use the acceleration formula: [tex]a=\frac{v_f-v_i}{t}[/tex]
a = acceleration (m/s²)vf = final velocity (m/s)vi = initial velocity (m/s)t = time (s)Based on the information given to us by the prompt, we know:
vi = 10 m/svf = 30 m/st = 4 sSubstitute these values for the variables to calculate the acceleration:
[tex]a=\frac{30-10}{4}\\\\a=\frac{20}{4}\\\\a=5[/tex]
Therefore, the acceleration of the bus is 5 m/s².
why do the other animals listen to old major speak in the barn late on night?
Part B After producing electricity in many different ways, describe what causes electricity to flow in the coil? In your response, describe the types of forces acting on the electrons and how they result in movement.
Explanation:
If a coil of wire is placed in a changing magnetic field, a current will be induced in the wire. ... A changing magnetic field through a coil of wire therefore must induce an emf in the coil which in turn causes current to flow.
Due to the flow of the current run, the coil magnetic field is produced. Magnetic fields result in magnetic force.
What is electric force?The electric force between the two charges is directly propotional to the product of the charge and inversly propotional to the square of the distance between them.
A current will be generated in a wire coil if it is put in a changing magnetic field. As a result, a changing magnetic field through a coil of wire must create an emf in the coil, causing the current to flow.
A current is induced in a coil of wire when it is put in a changing magnetic field. Something generates an electric field that drives the charges around the wire, causing the current to flow.
Hence due to the flow of the current in the coil magnetic field is produced.
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A pulley system is made of 3 pulley write its velocity ratio
Almost 3 times fast than normal pulley system
mark me
A stone is thrown into a pond. Five waves were made from the same source in 10 seconds.
The frequency of the wave for the stone thrown in the pond is 0.5Hertz.
The question does not specify what to calculate but we can look for the frequency of the wave.
Frequency is the number of oscillations completed in one second. This is interpreted as:
x oscillations = 1second
If Five waves were made from the same source in 10 seconds for a stone that is thrown inside the pond, then:
5 oscillations = 10seconds
Divide both expressions to get x (the required frequency)
x/5 =1/10
Cross multiply
10x = 5
Divide both sides by 10
10x/10 = 5/10
x = 1/2
x = 0.5Hertz
Hence the frequency of the wave is 0.5Hertz.
NB: The period of the wave is simply the reciprocal of the frequency.
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mercury is commonly used in thermometer give reasons
Answer:
hi
BECAUSE MERCURY IS USED BECAUSE IT is the only liquid available in room temperatureExplanation:
pls mark as a BRAINLIST
An airplane starts from rest and undergoes a uniform acceleration of 10.8 m/s^2 for 16.7 s seconds before leaving the ground. What is its displacement?
Answer:
3012.012m
Explanation:
s=it +1/2(10.8)(16.7)^2
difference between uniform motion and non uniform motion
Answer:
Uniform motion is a type of motion that is characterized as the motion of an object wherein the object moves in a straight line and its velocity remains unchanged along that line, regardless of the duration of time, as it occupies equal distances at equal time interval and Non-uniform motion is described as the motion of an object wherein the object moves at different speeds and does not cover the same distance at equal time intervals, regardless of the duration of the time interval.
Answer:
hope it's help you
Explanation:
In Uniform motion, the movement of a body is along the straight line with constant speed. In non uniform motion, the movement of a body is along the straight line with variable speed. In uniform motion, the body covers equal distance in an equal interval of time.
e. write unit of the following physical quantities
Answer:
electric current=ampere(A)
force=Newton (N)
area=metres square(m^2)
power=watt(w)
density=kg/m3
amount of substance =mole per cubic meter (mol/m3).
volume=cubic meter (m3),
Answer:
thanks for brainlist brother.........
9. Which of the following is NOT a recommendation to help you succeed in this course?
Consistently and actively work in the course on a daily basis.
Wait until the end of the semester to complete all work.
Complete all assignments in a timely manner.
Contact your instructor if you have questions.
Answer:
Wait until the end of the semester to complete all work.
Explanation:
this is the obvious answer.
please mark me brainliest
Answer:
Wait until the end of the semester to complete all work
Two stones are dropped from the edge of a 60m cliff , the second stone 1.6secon after the first . How far below the top of the cliff is the second stone when the separation between the two stone is 36m?
Answer:
The separation between the two stones is 36 m, when the second stone is approximately 10.9 m below the top of the cliff
Explanation:
The given parameters are;
The height of the cliff from which the stones are dropped, h = 60 m
The time at which the second stone is dropped = 1.6 seconds after the first
The distance below the top of the cliff when the distance between the two stones is 36 m = Required
We have;
The kinematic equation of motion that can be used is s = u·t - (1/2)·g·t²
For the first stone, we have, s₁ = u·t₁ - (1/2)·g·t₁²
For the second stone, we get; s₂ = u·t₂ - (1/2)·g·t₂²
t₁ = t₂ + 1.6
g = The acceleration due to gravity ≈ 9.81 m/s²
s = The distance below the cliff top
The initial velocity of the stones, u = 0
Let t represent the time from which the second stone is dropped at which the distance between the two stones is 36 m, we have;
s₁ = u·(t + 1.6) + (1/2)·g·(t + 1.6)²
s₂ = u·t + (1/2)·g·t²
u = 0
∴ s₁ - s₂ = 36 = (1/2)·g·(t + 1.6)² - (1/2)·g·t²
2 × 36/(g) = (t + 1.6)² - t² = t² + 3.2·t + 2.56 - t² = 3.2·t + 2.56
2 × 36/(9.81) = 3.2·t + 2.56
t = (2 × 36/(9.81) - 2.56)/3.2 = ≈ 1.49 s
t ≈ 1.49 s
s₂ = (1/2)·g·t²
∴ s₂ = (1/2) × 9.81 × 1.49² ≈ 10.9
The distance below the top of the cliff of the second stone when the the separation between the two stones is 36 m, s₂ ≈ 10.9 m.
A uniform, solid sphere of radius 2.50 cm and mass 4.75 kg starts with a purely translational speed of 3.00 m/s at the top of an inclined plane. The surface of the incline is 2.75 m long, and is tilted at an angle of 22.0∘ with respect to the horizontal. Assuming the sphere rolls without slipping down the incline, calculate the sphere's final translational speed v2 at the bottom of the ramp.
Answer:
The final translational seed at the bottom of the ramp is approximately 4.84 m/s
Explanation:
The given parameters are;
The radius of the sphere, R = 2.50 cm
The mass of the sphere, m = 4.75 kg
The translational speed at the top of the inclined plane, v = 3.00 m/s
The length of the inclined plane, l = 2.75 m
The angle at which the plane is tilted, θ = 22.0°
We have;
[tex]K_i[/tex] + [tex]U_i[/tex] = [tex]K_f[/tex] + [tex]U_f[/tex]
K = (1/2)×m×v²×(1 + I/(m·r²))
I = (2/5)·m·r²
K = (1/2)×m×v²×(1 + 2/5) = 7/10 × m×v²
U = m·g·h
h = l×sin(θ)
h = 2.75×sin(22.0°)
∴ 7/10×4.75×3.00² + 4.75×9.81×2.75×sin(22.0°) = 7/10 × 4.75×[tex]v_f[/tex]² + 0
7/10×4.75×3.00² + 4.75×9.81×2.75×sin(22.0°) ≈ 77.93
∴ 77.93 ≈ 7/10 × 4.75×[tex]v_f[/tex]²
[tex]v_f[/tex]² = 77.93/(7/10 × 4.75)
[tex]v_f[/tex] ≈ √(77.93/(7/10 × 4.75)) ≈ 4.84
The final translational seed at the bottom of the ramp, [tex]v_f[/tex] ≈ 4.84 m/s.
Which are characteristics of a prokaryotic cell? Select three options.
O contains DNA
O lacks DNA
O contains ribosomes
O lacks ribosomes
O contains a nucleus
O lacks a nucleus
I NEED THIS QUICKLY
Answer:
A. Contains DNA
C. Contains ribosomes
F. Lacks a nucleus
Explanation:
state the term used to describe the turning force exerted by the man pushing down on a lever to lift one end of a heavy log
The term used to describe the turning force exerted when pushing an object is effort.
What is effort?The is the input force or force applied at one point of a lever in order to overcome a load.
The relationship between effort, load and mechanical advantage of a lever is given as;
M.A = L/E
where;
M.A is mechanical advantageL is the loadE is the applied force or effortThus, the term used to describe the turning force exerted when pushing an object is effort.
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please help me with my question I will like and mark as brainliest for the first correct answer due tomorrow morning
Answer:
1845.26 ?
Explanation:
18.46 × 99.96= 1845.2616 = 1845.26
im not entirely sure though
An imaginary star is four light years from earth. The star has a planet, upon which a large mirror has been installed. The mirror faces earth. A ten year old boy aims his telescope at the mirror. How old will the boy be when he sees his own reflection?
Answer:
14 years
Explanation:
because the light will take four years to reach the earth. And the star is four light years away from the earth.
Hope that helps you please followAn imaginary star is four light years from earth. The star has a planet, upon which a large mirror has been installed. The mirror faces earth. A ten year old boy aims his telescope at the mirror,then the boy would be 14 years old when he will see his own reflection.
What is a light year?
It can be defined as the distance travelled by the light in one year .it is represented in units of distance such as miles or km.
1 light year is calculated by multiplying the speed of light with the time of one year
1 light year = speed of light × one year time period
1 light year = 3×10⁸ ×(365×24×60×60)
=9.461× 10¹⁵ meter
As given in the problem 10 year old boy aims his telescope at the mirror which is 4 light years away then the light has to travel four years to reach the boy ,then the boy would be 14 year old when he would see his own reflection.
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You toss an apple across the room to a friend. Which of the following statements is true about the apple at the top of its trajectory?
A. Its acceleration is zero.
B. The horizontal component of its velocity is zero.
C. The vertical component of its velocity is 9.8 m/s down.
D. Its acceleration is 9.8 m/s2 down.
Describe the laws of liquid pressure and Explain the term fluid. (Please give the correct answer, it's really urgent)
Answer:
The laws of liquid pressure are
(i) Pressure inside the liquid increases with the depth from the free surface of the liquid.
(ii) Pressure is same at all points on a horizontal plane, in case of stationary liquid.
(iii) Pressure is same in all directions about a point inside the liquid.
(iv) Pressure at same depth is different in different liquids. It increases with the increase in the density of the liquid.
(v) A liquid will always seek its own level.
A Fluid is any liquid or gas or generally any material that cannot sustain a tangential, or shearing, force when at rest.
Explanation:
Mercury is used in thermometer.Give reason
Answer:
Mercury is the only one in liquid state at room temperature
valancy of an atom is +2. what does it mean.
Answer: I hope you find it useful
Explanation: Group 2 elements have two valence electrons. The two valence electrons are easily lost in the formation of chemical bonds. Once the two electrons are lost, the atom then has a full outer shell and is therefore more stable.
so, if an atom has valency 2 , then it means that the atom can combine with 2 other atoms .
A 20 kg truck drives in a circle of radius 4 m at 10m/s. What causes
the circular motion?
A. Normal Force
B. Friction
C. Tension
D. Gravity
Answer:
Normal force
Explanation:
The force is centipetral forceCalculating :-
Mass=m=20kgRadius=r=4mVelocity=10m/s=vWe know
[tex]\boxed{\sf F_c=\dfrac{mv^2}{r}}[/tex]
[tex]\\ \sf\longmapsto F_c=\dfrac{20(10)^2}{4}[/tex]
[tex]\\ \sf\longmapsto F_c=\dfrac{20(100)}{4}[/tex]
[tex]\\ \sf\longmapsto F_c=\dfrac{2000}{4}[/tex]
[tex]\\ \sf\longmapsto F_c=500N[/tex]
6. 15. A boy takes 5 seconds to reach each point from ‘A’ to ‘B’, ‘B’ to ‘C’ and ‘C’ to ‘D’ as
shown in the diagram. If AB = BC = CD = 20 m then which of the following information is
correct when the boy reaches point D from point A via BC?
Explanation:
Could you also show the diagram
Solve for M₂
Base Equation: M₂ = Fr²/GM₁
F = 132N, G = 6.67 x 10⁻¹¹ Nm²/kg², r = .243m, and M₁ = 1.175 x 10⁴ kg, then what is M₂ = ?
Explanation:
M₂ = Fr²/GM₁
M₂ = [(132N)(.243m)²]/[(6.67*10^-11N*m²/kg)(1.175*10^4kg)]
M₂ = (7.79N*m²)/(7.84*10^-7N*m²)
M₂ = 9.94*10^6 kg
Joseph jogs from one end A to the other end B of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph's average speeds and velocities in jogging (a) from A to B and (b) from A to C?
Answer:
Explanation:
(a) It is given that Joseph jogs on a straight road of 300m in a time interval of 2 minutes and 30 seconds, which is equal to 150seconds. Therefore, when Joseph jogs from point A to point B, he covers a distance of 300m in time of 150seconds. Hence, his average speed is 300m/150s=2ms^−1. Since it is a straight road and he jogs in a single direction in this case, his displacement is equal to 300m. Since it is a straight road and he jogs in a single direction in this case, his displacement is equal to 300m.
Hence, his average velocity is 300m/150s=2ms^−1
(b) Then it is given that he turns back and points B and jogs on the same road but in the opposite direction for a time interval for 1 minute and covers a distance of 100m.If we consider the whole motion of Joseph, i.e. from point A to point C, then he covers a total distance of 300m+100m=400m. And he covers this total distance in a time interval of 2.5min+1min=3.5min=210s.
Therefore, his average speed for this journey is 400m210s=1.9ms−1.
For the same journey is displacement is equal to the distance between the points A and C,i.e. 300m−100m=200m.
Hence, his average velocity for this case is 200m/210s=0.95ms^−1
Derive the following equations. :a=u-v by t
5. Which one of the following factors is directly proportional to density of liquid? (a) Temperature (b) Volume of liquid (c) Upthrust (d) Density of object
Answer:
A
The upthrust on a floating body is in upwards direction and is equal to the weight of the liquid displaced
B
The upthrust is directly proportional to the density of the liquid in which the solid is immersed
C
The upthrust is directly proportional to the volume of the fluid displaced by a solid
The upthrust acts on the body in upward direction at the center of buoyancy.
Upthrust is equal to the weight of liquid displaced by object and weight of liquid will depend on its density.
Upthrust is F=Vρg ,where V is the volume of liquid displaced and ρ is the density of fluid.
The total lateral pressure acting on an immersed object on one side is equal and in opposite direction to the total lateral pressure acting on the other side.
Give reason.
b} String roller is an example of wheel and axel .Why?
Explanation:
string roller is called an example of wheel and axel because The thin rod which needs to be turned is called the axle and the wider object fixed to the axle, on which we apply force is called the wheel.
hence the we apply force on the roller and the string gets tight.
A bike travels at 3.0 m/s, and then accelerates to a speed of
8.5 m/s in a time of 2.5 seconds. The average acceleration of
the bike is
m/s2
The average acceleration of the bike is 2.2 m/s²
What is average acceleration?Acceleration, rate at which velocity changes with time, in terms of both speed and direction.
A point or an object moving in a straight line is accelerated if it speeds up or slows down.
According to the question,
Given, initial velocity, u=3.0m/s and final velocity v=8.5 m/s
Time = 2.5 seconds
If a be the acceleration.
a = [tex]\frac{v-u}{t}[/tex]
a = [tex]\frac{8.5 - 3.0}{2.5s}[/tex]
⟹ a=2.2 m/s²
So, The average acceleration of the bike is 2.2 m/s²
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An empty cardboard box falls from a high platform. Through the use of special equipment it was found that the energy of the cardboard box at the top of the fall was more than the energy of the box at the bottom of the fall. Explain.
Answer:
The mechanical energy of the cardboard box, M.E. = K.E. + P.E.
Where;
P.E. = The potential energy of the cardboard box = m·g·h
K.E. = The kinetic energy of the cardboard box = (1/2)·m·v²
Where;
m = Mass of the cardboard box
g = The (constant) acceleration due to gravity ≈ 9.81 m/s²
h = The height of the cardboard box
v = The velocity of the cardboard box
At the top of the fall, where h = The height of the platform = [tex]h_{platform}[/tex], and v = 0 (the box is initially at rest at the top), the M.E. is given as follows;
[tex]M.E._{top}[/tex] = P.E. + K.E. = m·g·[tex]h_{platform}[/tex] + (1/2) × m × 0² = m·g·[tex]h_{platform}[/tex]
However, at the bottom of the fall, the height of the box, h = 0, the velocity of the box, v = 0, therefore, the total energy at the bottom, after the box comes to rest, [tex]M.E._{bottom}[/tex] = 0
Therefore;
The total energy of the box at the top of the fall, .[tex]M.E._{top}[/tex] = m·g·[tex]h_{platform}[/tex] was more than the total energy of the box at the bottom of the fall,
[tex]M.E._{bottom}[/tex] = 0
Explanation:
