lubricants reduce friction by replacing sliding friction with fluid friction
A puck is travelling at a speed of 28 m/s. If it has a mass of 200 g, what is its momentum?
Answer:
Explanation:
Momentum is equal to mass times velocity:
p = mv; therefore,
p = .200(28) and
p = 5.6 [tex]\frac{kg*m}{s}[/tex]
A car takes a full round of journey in a roundabout with constant speed, as the driver got confused with the route. Can we consider it as a uniform motion? Why?
Answer: The given statement is True
Explanation:
A uniform motion is defined as the motion where an object is moving at a constant speed.
A non-uniform motion is defined as the motion where an object keeps changing its position and does not move at a constant speed.
We are given:
A car takes a full round of journey in a roundabout with constant speed
As the speed remains constant in a circular path, it is considered a uniform motion.
Hence, the given statement is True
A sled with mass 11.00 kg moves in a straight line on a frictionless horizontal surface. At one point in its path, its speed is 4.00 m/s; after it has traveled a distance 3.00 m beyond this point, its speed is 7.00 m/s. Use the work-energy theorem to find the force acting on the sled, assuming that this force is constant and that it acts in the direction of the sled's motion.
Answer:
The magnitude of the force acting on the sled is 60.5 newtons.
Explanation:
The Work-Energy Theorem states that the work done by the external force applied on the sled ([tex]W[/tex]), in joules, is equal to the change of its translational kinetic energy ([tex]\Delta K[/tex]), in joules:
[tex]W = \Delta K[/tex] (1)
By definitions of work and translational kinetic energy we expand the equation above:
[tex]F\cdot s = \frac{1}{2}\cdot m\cdot (v_{2}^{2}-v_{1}^{2})[/tex] (1b)
Where:
[tex]F[/tex] - External force applied on the sled, in newtons.
[tex]s[/tex] - Travelled distance, in meters.
[tex]v_{1}, v_{2}[/tex] - Initial and final velocities, in meters per second.
If we know that [tex]m = 11\,kg[/tex], [tex]v_{1} = 4\,\frac{m}{s}[/tex], [tex]v_{2} = 7\,\frac{m}{s}[/tex] and [tex]s = 3\,m[/tex], then the external force applied on the sled is:
[tex]F = \frac{m\cdot (v_{2}^{2}-v_{1}^{2})}{2\cdot s}[/tex]
[tex]F = \frac{(11\,kg)\cdot \left[\left(7\,\frac{m}{s} \right)^{2}-\left(4\,\frac{m}{s} \right)^{2}\right]}{2\cdot (3\,m)}[/tex]
[tex]F = 60.5\,N[/tex]
The magnitude of the force acting on the sled is 60.5 newtons.
Which of the following statements is incorrect?
1) A ray of light travels from a point A to point B in a path that takes the shortest time
2) In reflection angle of incidence equal to angle of reflection
3) Magnification for a plane mirror is always unity
4) A plane mirror can form only virtual images
Answer:
2
Explanation:
in reflection the incident ray and reflected rays are equal an angle
QUESTION 30 A tennis ball moves back and forth 10 times in 5 sec. The frequency of its motion is
Answer:
so in 1 sec 2 times
so frequency = 2
Explanation:
Hai tiếp điểm hình trụ bằng đồng có đầu hình cầu bán kính R = 70mm, lực ép tiếp điểm F = 100N, Mô đun đàn hồi của đồng là 11.8 * 106(N/cm2). Cho biết: a = 0.86 * (F*R/E)1/3, điện trở suất của đồng là 1.62 * 10-8 (Ω/m), với tiếp điểm đồng thì hệ số K1 = 3,16.10-4 (ΩN1/2). Biết các giá trị ứng suất của đồng là: σdh = 38300 N/cm2; σdẻo = 45000 N/cm2; σd.Nát = 51000 N/cm2. Tính điện trở tiếp xúc trong trường hợp thỏa mãn điều kiện tản dòng lí tưởng và trong trường hợp thực nghiệm.
Answer:
5dhydydyeze6ese6z7zuezuze6ezyezyezzeze
In this experiment, the ______ was intentionally manipulated. This was the independent variable.
A. fan speed
B. mass
C. acceleration
Answer:
Fan speed
Explanation:
because is the dependent variable
True or false please help I’ll give brainliest
Answer:
All of them are false
Explanation:
4. electrons flow from earth to the object
5. electrons move freely
6. protons can't move
Answer:
They all false
The
push switch is closed and the door unlocks. Explain in detail how this happens.
Answer:
The push switch is closed and the door unlocks. ... The switch completes the circuit and a current flows through the coil. The coil becomes an electromagnet and its iron core becomes magnetised. The iron bolt is attracted to the electromagnet.
Explanation:
Please Mark me brainliest
Can someone help me with this? I will give brainliest! Ridiculous answers will be reported. Thank you.
Give atleast (5) etypes of cleaning tools , equipment,supplies, and materials that you can find either in your home or school. Identify each use
Answer and Explanation:
Cleaning tools, equipment, supplies, and materials that can be easily found in a school in one each are: scrub brush, sponges, buckets and brooms.
These equipments are essential to promote a clean, organized and safe environment and for this reason, they can be easily found both at school and in a home, since the cleanliness of these two places is essential for the well-being, proactivity and health of the people who attend them.
Activity 1 MATCH IT
Directions: Match Column A to Column B. Write your answer on the space provided before the number.
COLUMN A
__1. Hiking
__2. Orienteering
__3. Zumba
__4. Volleyball
__5.badminton
COLUMN B
A. It is an outdoor navigational recreational activity using specially drawn and detailed maps.
B. Created through on-the –spot aerobics class using the non- traditional music.
C.Going on an extended walk for the purpose of pleasure and exercise.
D. Can be traced from the ingenuity of William J. Morgan in 1895 at Holyoke Massachusetts.
E. Games are held inside the gym to avoid the effect of air in the flight of the shuttle.
Answer:
1. A hiking
2. C
3. B
4. D
5. E
The three scientists credited with using all available data and correctly determing the sturcture of dna from many years of previous work are
Answer:
James Watson, Francis Crick, and Maurice Wilkins
Explanation:
The three scientists that used the available data ( x-ray images of DNA provided by Rosalind Franklin) to correctly determine the structure of DNA are : James Watson, Francis Crick, and Maurice Wilkins.
These scientists discovered the structure of DNA in 1953 and they received, and they receive a Nobel Prize in Physiology or Medicine for their discovery
Change the following as indicated in the brackets.
8m (km,cm)
metres to kilometres = 1/1000
8 m ⇒ 0.008 km
metres to centimetres = × 100
8 m ⇒ 800 cm
Answer:
1000m=1km
so, 8m=8/1000 = 0.008km
1m=100cm
so, 8m=8×100=800
a body of mass 5kg moving on a horizontal ground has a coefficient of friction 0.36.find the normal reaction acting on the body?
Answer:
50 N.
Explanation:
From the question given above, the following data were obtained:
Mass (m) = 5 Kg
Coefficient of friction (μ) = 0.36
Normal reaction (N) =?
Next, we shall determine the weight of the body. This can be obtained as follow:
Mass (m) = 5 Kg
Acceleration due to gravity (g) = 10 m/s²
Weight (W) =?
W = mg
W = 5 × 10
W = 50 N
Finally, we shall determine the normal reaction. This can be obtained as follow:
Weight (W) = 50 N
Normal reaction (N) =?
Normal reaction = weight of the body
N = W = 50 N
Thus, the normal reaction acting on the body is 50 N
A box at rest is in a state of equilibrium half way up on a ramp. The ramp has an incline of 42° . What is the force of static friction acting on the box if box has a gravitational force of 112.1 N ?
70 N
80 N
75 N
85 N
Answer:
the correct answer is 75 N
Explanation:
This is a translational balancing exercise, let's set a reference system with the x-axis in the direction of the plane and the y-axis perpendicular to the plane.
In this reference system the force to decompose is the weight
sin 42 = Wₓ / W
cos 42 = W_y / W
Wₓ = W sin 42
W_y = W cos 42
Wₓ = 112.1 sin 42 = 75.0 N
W_y = 112.1 cos 42 = 83.3 N
The expression for equilibrium on the x-axis is
Wₓ - fr = 0
fr = Wₓ
fr = 75.0 N
the correct answer is 75 N
A constellation’s changing position in the sky, at the same time of the evening, over a period of several weeks is evidence that:
a- Earth is round b- Earth’s axis is tilted. c- Earth rotates on its axis.
d- Earth revolves around the sun.
Answer:
d- Earth revolves around the sun.
Explanation:
Earth rotation can be defined as the amount of time taken by planet earth to complete its spinning movement on its axis.
This ultimately implies that, the rotation of earth refers to the time taken by earth to rotate once on its axis. One spinning movement of the earth on its axis takes approximately 24 hours to complete with respect to the sun.
On the other hand, earth revolution can be defined as a complete trip along a path around the sun. This path is known as an orbit and it typically takes the Earth 365¼ days to complete it's journey around the Sun.
When a constellation (stars) changes its position in the sky, at the same time of the evening and over a period of several weeks; it ultimately implies or is an evidence that Earth revolves around the sun.
A horse pulls a wagon with a force of 200 N for a distance of 80 m. How much work
does the horse do?
Answer:
w=f×s
w = 16000 J, hope this helps
what is time write its SI unit
15. You are watching a baseball game on television that 15
being broadcast from 4500 km away. The batter hits
the ball with a loud "crack" of the bat. A microphone
is located 22 m from the batter, and you are 2.0 m from
the television set. On a day when sound travels 343 m/s
in air, what is the minimum time it takes for you to hear
the crack of the bat after the batter hits the ball?
Answer:
t_total = 6.99 s
Explanation:
It asks us how long it takes to hear the sound, for this we must look for the time (t₁) it takes for the sound to reach the microphone, the time it takes for the video signal (t₂) to reach the television and the time (₃) it takes for the TV sound to reach us, so the total delay time is
t_total = t₁ + t₂ + t₂
we look for t1, it indicates that the distance x = 22m
v = x / t
t = x / v
t₁ = 22/343
t₁ = 6.41 10-2 s
time t₂
t₂ = 4500 103/3 108
t₂ = 1.5 10-5 s
time t₃
t₃ = 2/343
t₃ = 5.83 10⁻³
Total time is
t_total = t₁ + t₂ + t₃
t_total = 6.41 10⁻² + 1.5 10⁻⁵ + 0.583 10⁻²
t_total = 6.99 s
Atividade 1) A presença do campo magnético terrestre proporciona alguns efeitos interessantes. Dentre eles estão as auroras polares. Faça uma pesquisa e explique como esse fenômeno ocorre. Atividade 2 Utilizando a simulação mostrada na figura abaixo, aproxime o ímã da bússola em várias posições ao longo do plano. a) O que representam as pequenas agulhas ao redor do ímã? b) O que acontece com a agulha da bússola quando o ímã é movimentado ao seu redor? c) Marque a seleção "Mostrar medidor de campo". Movimente o medidor de campo O que você observa em relação ao campo magnético⃗ , quando o medidor de campo se aproxima do imã? c) Marque a caixa de seleção "planeta Terra". Como são mostradas as polaridades do ímã? Por que aparece dessa forma?
On which planet would your weight be the most and the least?
a) Jupiter and Mercury
b. Jupiter and neptune
c. Saturn and Neptune
d. Saturn and uranus
Answer:
Jupiter and neptune
Explanation:
if a train starts from rest and attains a velocity of 100m/s in 25 seconds. calculate the acceleration produced by the train.
help....................
What happens when two polarizers are placed in a straight line, one behind the other?
A. They allow light to pass only if they are polarized in exactly the same direction.
B. They block all light if they are polarized in exactly the same direction.
C. They allow light to pass only if their directions of polarizations are exactly 90° apart.
D. They block all light if their directions of polarizations are exactly 90° apart.
E. They block all light If their directions of polarizations are either exactly the same or exactly 90° apart.
Aiden is writing a report about the structure of the atom. In her report, she says that the atom has three main parts and two subatomic particles. Do you agree with her? Why or why not?
Answer:
I don't agree
Explanation:
Atoms have 3 subatomic particles protons, electrons and neutrons,
A student connects a small solar panel to a 40 a resistor to make a simple circuit. The solar panel produces a voltage of 2 0.
a Calculate the current in the student's circuit.
Ohm's law states that :
[tex]v = ir[/tex]the terms used are :
[tex]r = resistance[/tex][tex]v = potential \: \: difference[/tex][tex]i = current[/tex]let's solve for electric current :
[tex]2 = i \times 40[/tex][tex]i = \dfrac{2}{40} [/tex][tex]i = 0.05 \: A[/tex][tex]i = 50 \: mA[/tex][tex]\mathfrak{good\: \: luck \: \: for \: \: your \: \: assignment}[/tex]
Susan claims that she can throw a dart at a dartboard from a distance of 3.0m and hit the 5.0cm wide bull's-eye if she throws horizontally with a speed of 20 m/s. She starts to throw at the same height as the top of the bull's-eye. Will Susan hit the bull's-eye?
What is being asked? How to calculate?
The hull of a sunken boat, laying on the seabed, is 9 m below the surface of the sea, where the sea water has an average density of 1,025 kg/m3. The hull’s surface area is 12 m2. What is the total force exerted by seawater on the hull?Required to answer. Single line text.
Answer:
1084860 N
Explanation:
Applying,
P = ρgh................ Equation 1
Where P = pressure, ρ = density, h = height, g = acceleration due to gravity.
From the question,
Given: ρ = 1025 kg/m³, h = 9 m
Constant: g = 9.8 m/s²
Substitute these values into equation 1
P = (1025)(9)(9.8)
P = 90405 N/m²
Also,
P = F/A.............. Equation 2
Where, F = Force, A = Area.
Make F the subject of the equation
F = PA............... Equation 2
Given: A = 12m²
F = 12(90405)
F = 1084860 N
