We know
[tex]\boxed{\sf a=\dfrac{v-u}{t}}[/tex]
[tex]\\ \sf\longmapsto t=\dfrac{v-u}{a}[/tex]
[tex]\\ \sf\longmapsto t=\dfrac{18-80}{-16}[/tex]
[tex]\\ \sf\longmapsto t=\dfrac{-62}{16}[/tex]
[tex]\\ \sf\longmapsto t=3.8s[/tex]
(6). A car travels in a straight line from city A to city B at a speed of 60kmh-1
. Then return
from city B to city A along the original route at a speed of 40kmh-1
. The distance between
the two cities is 120 km. What is the average speed of the vehicle?
1. 30kmh-1
2. 45kmh-1
3. 48kmh-1
4. 60kmh-1
một oto đang chạy với vận tốc là 10m/s thì tăng tốc và chuyển động nhanh dần đều sau 20s thì đạt vận tốc 14m/s
a) tính gia tốc của xe
b) tính vận tốc xe sau 40s kể từ khi tăng tốc và quãng đường xe đi được trong thời gian đó
a) gia tốc = vf-vi / t
a = 14-10 / 20
a = 0,2ms⁻²
b) dưới dạng a = Δv / t
v = lúc
v = 0,2 × 40
v = 8ms⁻¹
như v = d / t
do đó d = vt
d = 8 × 40
d = 320m
hãy đánh dấu là trí óc nhất
HELP ME
Which two changes to the can opener would increase its mechanical efficiency?
A shorten the paddle so that they are closer in size to the axle that they turn
B grease the rotating wheel of the opener so that there is less breaks in between moving parts
C replaced it with a straight handle the act as levers with shorter pieces of metal
D sand the cutting surface of the metal piece so that it is perfectly smooth and sharp
Answer:
I THINK IT'S D....
HOPE SO
A 0.0780 kg lemming runs off a
5.36 m high cliff at 4.84 m/s. What
is its potential energy (PE) when it
jumps?
Answer:
4.097 Joules
Explanation:
Applying,
P.E = mgh............... Equation 1
Where P.E = Potential energy, m = lemming mass, h = height, g = acceleration due to gravity
From the question,
Given: m = 0.0780 kg, h = 5.36 m
Constant: g = 9.8 m/s²
Substitute these values into equation 1
P.E = 0.0780(9.8)(5.36)
P.E = 4.097 Joules.
Hence the potential energy is 4.097 Joules
Answer:
4.097 J
Explanation:
Based on its location on the periodic table, which element is the best
electrical insulator?
A. Iron (Fe)
O B. Sulfur (S)
O C. Calcium (Ca)
D. Silver (Ag)
Answer:
B
Explanation:
Nonmetal is better insulator than metals
Answer:
B
Explanation:
Just took the quiz.
4. diference between VR and efficiency
Answer:
Velocity ratio of simple machine is the ratio of distance travelled by effort to the distance travelled by load in the machine. The efficiency of a simple machine is defined as the ratio of useful work done by machine (output work) to the total work put into the machine (input work).
Explain how a submarine
floats on the water surface
and dives down into water.
Answer:
A submarine uses tanks that are filled with compressed air and when it is needed the air is released and takes on water which increase the density making it sink but when the water is pushed out the sub marine density is decreased making it float
25 POINTS 25 POINTS 25 POINTS 25 POINTS 25 POINTS
Assignment: Build an Electromagnet and a Motor Investigation
Electromagnet
1. How many paper clips did the wire wrapped around the nail just a few times pick up?
2. Which electromagnet design was most successful in picking up the most paper clips?
3. Would wrapping the wire more times around the nail make the electromagnet stronger or weaker?
4. What do you think the result would be if an iron nail that was much thicker was used?
5. What do you think would happen if a wooden stick was chosen as the core instead of the iron nail?
Motor
1. Describe the components that are necessary to make a motor run? What do they each provide? (example: battery provides voltage source)
2. Describe how the homemade motor makes mechanical energy from electrical energy.
3. What are three appliances in your house that use a motor that turns electrical energy into mechanical energy?
All the paper clips, coiled wire with nail and wrapping or coiling the wire more times are the correct answers.
All the paper clips will the wire wrapped around the nail just a few times pick up. A coiled wire with nail in the center is the electromagnet design which is most successful in picking up the most paper clips. Wrapping or coiling the wire more times around the nail make the electromagnet more stronger.
If an iron nail that was much thicker was used, it will make the magnet stronger that leads to strong electromagnetism. There are three main parts that is necessary for making a motor i.e. a rotor, a stator and a commutator.
These three parts use the attractive and repulsive forces of electromagnetism, causing the motor to spin continually as long as it receives a steady flow of electric current. Motors comprise of loops of wire in a magnetic field.
When current is passed through the loops, the magnetic field exerts a torque on the loops, which rotates the shaft that leads to the generation of electricity. Water pump, mixer and washing machine are three appliances in your house that use a motor that turns electrical energy into mechanical energy.
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The needle in the following diagram rotates around a fixed point in the middle. Based on the information given, what way will the needle rotate when the current is applied?
Answer:
nods 40th anniversary rid off e 49en9 snns
Calculate the acceleration of a train of mass 30 000 kg when driven by a force of 15000 N.
Answer:
Explanation:
F = ma, so filling in:
15000 = 30000a and
a = .50 m/s/s
The acceleration of a train is 0.50 [tex]m/s^{2}[/tex].
What is acceleration?Acceleration is the rate of change of the velocity of an object with respect to time.
F = ma
a = F/m
a = 15000/30000
a = 0.50 [tex]m/s^{2}[/tex]
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28 Why is soft iron used for the core of an electromagnet?
А Soft iron easily becomes a permanent magnet.
B Soft iron is a good electrical conductor.
с Soft iron is a poor thermal conductor.
D Soft iron loses its magnetism when the current in the coil is switched off.
Answer:
An electromagnet is a form of magnet that is made by the passage of electric current through a coil of wire. The core of an electromagnet increases the strength of the produced magnetic field
Soft iron is used as the core of an electromagnet because soft iron is a magnetic material and therefore it is permeable to and becomes magnetized by the magnetic field coming from the flowing current, thereby allowing more flux to pass through the core of the electromagnet, producing a magnetic field strength that is several times that of an air core electromagnet as the relative permeability (to magnetic flux, compared to vacuum) of soft iron is about 64 × 10³
However, once the current is switched, the soft iron does not remain its magnetic, and therefore, the electromagnet becomes demagnetized, thereby being able to maintain its electromagnetic characteristics (being made magnetic by the flow of electric current)
Explanation:
Which statement about the ocean is true?
No evaporation or precipitation in the water cycle occurs over the ocean.
Most evaporation and precipitation in the water cycle occur over the ocean.
All evaporation and precipitation in the water cycle occur over the ocean.
Evaporation, but not precipitation, in the water cycle occurs over the ocean.
Answer:
most evaporation and precipitation in the water cycle occus over the ocean
The option Most evaporation and precipitation in the water cycle occur over the ocean. is the correct answer
Describe the laws of liquid pressure and explain the term fluid. (Please try to give the correct answer 'coz it's urgent!)
Answer:
The laws of liquid pressure are: ... The liquid pressure at a point inside the liquid is same in all directions. The liquid pressure at a point inside the liquid is directly proportional to the depth of that point from the free surface of liquid. The pressure of liquid at same depth is different for different liquids
Answer:
The laws of liquid pressure:
The pressure that is inside the liquid rises with the intensity from the surface of a liquid.
The term fluid:
Fluid is basically liquid and a substance that is known to have no certain shape. The opposite of the term fluid would be solid.
một hòn đá có khối lượng 5kg bay với vận tốc 72kg/h . động lượng của hòn đá là
Answer:
Momentum = 100 Kgm/s
Explanation:
Given the following data;
Speed = 72 km/h
Mass = 5 kg
To find the momentum of the stone;
First of all, we would have to convert the value of speed to meter per seconds.
Conversion:
72 km/h to m/s = (72 * 1000)/3600 = 20 m/s
Momentum can be defined as the multiplication (product) of the mass possessed by an object and its velocity. Momentum is considered to be a vector quantity because it has both magnitude and direction.
Mathematically, momentum is given by the formula;
Momentum = mass * velocity
Substituting the values into the formula, we have;
Momentum = 5 * 20
Momentum = 100 Kgm/s
The gravitational force of the two objects is 6.67x10-11N. Explain this statement.
Answer:
it means that the force of attraction between two object in gravitation is 6.67×10-11N
It means that the force of attraction between two object in gravitation is 6.67×10-11N.
What is the formula of mass in gravitational force?The formula is g = GM/r2, Where M is the mass of the Earth, r is the radius of the Earth (or distance between the center of the Earth and you, standing on its surface), and G is the gravitational constant. G (without the subscripts) is the gravitational constant, and c is the speed of light.
What is the gravitational force between two objects?The gravitational force between two objects is proportional to their masses and inversely proportional to the square of the distance between their centers. joining the two centers of masses.
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A man has 60w bulbs and a 240w water heater in his apartment. If the bulbs and the water heater are switched on for four hours daily and the cost of electricity is N1.20 per KWh calculare his bill in 30 days
Answer: [tex]N43.2[/tex]
Explanation:
Given
Power consumption of bulb and water are [tex]60\ W[/tex] and [tex]240\ W[/tex]
If the Devices are on for four hours
Total power of devices [tex]60+240=300\ W[/tex]
Energy consumed for 4 hours is
[tex]\Rightarrow 300\times 4=1200 Wh\\\Rightarrow 1.2\ kWh[/tex]
For 30 days it is [tex]1.2\times 30=36\ kWh[/tex]
Cost for 30 days [tex]36\times 1.2=43.2\ N[/tex]
A rocket blasts off. In 10.0 seconds it is at 10,000 ft, traveling at 3600 mph. Assuming the direction is up, calculate the acceleration.
Answer:
Explanation:
Givens
t = 10 seconds
vi = 0
vf = 3600 mph
a = ?
d = 10000 feet
Formula
a = (vf - vi)/t
Solution
vf = 3600 mph * 1 hr / 3600 seconds * 5280 feet / 1 mile = 5280 ft / sec
a = (5280 - 0)/10
a = 528 ft/sec^2
if you rub a ballon with wool or duster it can charge it negatively where do these extre charge come from?
Answer:
The electrons come from the free electrons in wool which contains moisture or other forms of additives that creates impurity centers which causes the wool to be electrically conductive
Explanation:
Wool which is mixed with certain substances, conducts electricity in a manner similar to the wool-water system that give rise to centers of impurities where electrical conduction takes place
The ability to conduct electricity is related to the presence of free electrons on a material. Therefore, when a balloon, which is an insulator, is rubbed with wool, some of the mobile electrons on wool, which is also an insulator without the presence of substances that aid its electrical conductivity, are transferred to the balloon, thereby making the balloon to be negatively charged
A bullet of mass of 50g is moving with the velocity of 200km/h .calculate the kinetic energy of the bullet .
Answer:
is 10³
Explanation:
cuz the formula of KE is 1/2mv²
covert 50g to kg first then plug in the formula
1/2 × 0.05 × 200 = 10³ J
Why are houses in hot areas painted in white while those in cold areas painted with dull colours
Answer:
Because white color reflects back the heat coming from the sun while dull colors absorb the heat.
the unit of force and pressure are called derived unit
Answer:
yes
Explanation:
because they can be derived in the form of base units
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.
20.In case the conductor is a heating appliance, then this energy(w) is converted into heat(H) i.e
A. w=H C. w=I2Rt
B. w=VIt D. all of above
Answer:
not sure just need points
Explanation:
a+b+c
A person carries a box of 100 kg. What is the weight of the box? (g= 9.8 m/s2)
Answer:
980 newton
Explanation:
100×9.8 = 980
Plutonium-32 has a half-life of 14.2 days. After 99.4 days, how much of what was originally a 499.2 gram sample remains?
14 grams
3.9 grams
35.7 grams
0.71 grams
Answer:
3.9 gm remains
Explanation:
499.2 ( 1/2)^(99.4/14.2) = 3.9 gm
What will happen to the velocity and momentum of each ball when the small ball hits the heavier large ball?
The small ball will transfer its momentum to the heavier ball. Since the momentum gets conserved. The velocity will depend upon the mass of the balls.
What is the law of conservation of momentum?According to the law of conservation of momentum. The momentum of the body before the collision is always equal to the momentum of the body after the collision.
The momentum of the body is given by the product of the mass and velocity of the body.
According to the law of conservation of momentum
Momentum before collision =Momentum after collision
Hence the small ball will transfer its momentum to the heavier ball.
To learn more about the law of conservation of momentum refer;
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can anyone please help me
Answer:its most likely c
Explanation:
How can you say gravitational force is a field force
Answer:
because gravity pulled us in the land if there is no gravitational force there will not be field force too
Explanation:
hope it's will help you
A magnet falls through a loop of wire with the south pole entering first. After it has fallen all the way through the wire loop so that the north pole end is moving away from the loop, what is the direction of the induced current in the loop (as viewed from above, looking down on the magnet)
Answer:
The induced current direction as viewed is clockwise
Explanation:
Lenz's Law states that the induced e. m. f. causes current to be driven in the loop of wire in such a way as to generate magnetic field that are oppose the magnetic flux change which is the source of the induced current
Therefore, as the magnet approaches the coil with the south pole, the coil produces current equivalent to the upward movement of the south pole of a permanent magnet through it which according to Flemings Right Hand Rule is clockwise
Therefore;
The direction of the induced current in the loop (as viewed from above, looking down the magnet) is clockwise
Use the equation d=st where d= distance, s= speed, and t= time. If you ride a skateboard at a speed of 8m/s for 12 seconds, how far do you travel
Answer:
96 meters
Explanation:
d = st
d = (8 m/s)(12 s)
d = 96 m
