Answer:
n an electrometer, it is built in such a way that its resistance in parallel is extremely high
Ground in a circuit is a reference point from which voltages are measured
all the instruments must be grounded and we must ground ourselves
Explanation:
When you build a voltmeter you have a resistance in parallel with the galvanometer, therefore when measuring the voltage of a circuit, so that there is no effect (load effect) by the voltmeter, a resistance must be much greater than the resistance where it is is measuring.
In an electrometer, it is built in such a way that its resistance in parallel is extremely high in the order of 10¹²Ω, so its load effect is very small and can be measured with high resistance mu
Electric ground in home and industrial installations is a protection system consisting of a metal piece connected to a buried ground electrode.
Ground in a circuit is a reference point from which voltages are measured and is common to all parts of the circuit
In an experiment where an electrometer is used, all the instruments must be grounded and we must ground ourselves, since it must be an instrument where very small voltages are measured at high impedances.
The group that receives treatment is called the?
Tested Group
Control Group
Placebo Group
Experimental Group
Answer:
experimental group
Explanation:
please mark me as a brainlist..
Answer:
Experemtial group
Explanation:
The placebo is just sugar pills tested is ones already done and control is a mix of the two
A car runs around a circular race track from the point A to diametrically opposite point B The radius of the circle is ‘r’ . The distance traveled by the car is ________ the displacement of the car is _________ show your work!
Answer:
Distance = πr
Displacement = 2r
Explanation:
First we need to find the distance covered by the car. As the car is travelling on a circular path and it traveled to a diametrically opposite point on the circular path. Therefore, the distance covered by the car must be the half value of the circumference.
Distance = Circumference/2
Distance = 2πr/2
Distance = πr
Since, displacement is the straight line distance between two points. So, the displacement in moving from a point to its diametrically opposite point must be equal to the diameter of circle:
Displacement = Diameter
Displacement = 2r
Which atom is most likely to accept electrons to form an ionic bond? a mercury ion with a negative 2 charge a potassium ion with a negative 1 charge radon, a noble gas with 8 valence electrons sulfur, a nonmetal with 6 valence electrons
Sulfur, a nonmetal with 6 valence electrons atom is most likely to accept electrons to form an ionic bond option (D) correct.
What is an ionic bond?Ionic bonds, also known as electrovalent bonds, are a type of connection created in a chemical molecule by the electrostatic attraction of ions with opposing charges.
As we know,
It has been shown that the top of the electronegativity scale is defined by the fundamental atomic particles F>O>N.
Ionic bonds need an electron, often a nonmetal, and an electron, typically a metal. Metals display ionic bonding because there aren't many-electron in outer orbitals.
Thus, sulfur, a nonmetal with 6 valence electrons atom is most likely to accept electrons to form an ionic bond option (D) correct.
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what is machinery
............
Two forces P and Q act on an object of mass 7.00 kg with Q being the larger of the two forces. When both forces are directed to the left, the magnitude of the acceleration of the object is 1.30 m/s2. However, when the force P is directed to the left and the force Q is directed to the right, the object has an acceleration of 0.600 m/s2 to the right. Find the magnitudes of the two forces P and Q in newtons.
Answer:
P = 2.45 N
Q = 6.65 N
Explanation:
According to Newton's 2nd Law:
Unbalanced Force = ma
where,
m = mass = 7 kg
a = acceleration
In the first case when both forces P and Q act on left side:
Unbalanced Force = P + Q
a = 1.3 m/s²
Therefore,
P + Q = (7 kg)(1.3 m/s²)
P + Q = 9.1 N ------------------------- equation 1
Now, in second case when both forces have different directions:
Unbalanced Force = Greater Force - Smaller Force
Unbalanced Force = Q - P
a = 0.6 m/s²
Therefore,
Q - P = (7 kg)(0.6 m/s²)
Q - P = 4.2 N ------------------- equation 2
Adding equation 1 and equation 2, we get:
(Q + P) + (Q - P) = 9.1 N + 4.2 N
2 Q = 13.3 N
Q = 6.65 N
Using this value in equation 2, we get:
6.65 N - P = 4.2 N
P = 2.45 N
What the answers due in 2 min
Hello ┬┴┬┴┤◕3◕)づ├┬┴┬┴
The answer is 3 m
the gap in between 4s and 6s is 5s
you follow your finger up to the purple like, and follow the purple line in a straight line to the left. It ends at 3m and that is your answer.
Which of the following is the best description of a gaseous substance?
It's the result of a chemical reaction involving two or more elements.
It has no definite shape or volume and will expand indefinitely.
It holds its shape without outside restraint.
It has no shape of its own but has a definite volume.
The best description of a gaseous substance is : (B). It has no definite shape or volume and will expand indefinitely.
Meaning of a gaseous substanceA gaseous substance can be defined as a substance that is gaseous in nature or exhibit gaseous properties
A gaseous substance is just like a gas that its particles have unrestricted movement and the force of attraction between the particles are very weak or negligible.
In conclusion, The best description of a gaseous substance is : (B). It has no definite shape or volume and will expand indefinitely.
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Genes are section of DNA that code for a particular trait. Genes are
Answer:
a gene is the basic physical and functional unit of heredity.
Genes are section of DNA that code for a particular trait. Genes are basic unit of inheritance in all living things specifying the physical and biological traits.
What are genes ?The precise meaning of the term "gene" has long been a topic of discussion in science. Here's an easy way to think about it: Our cells and tissues are built with proteins as the foundation. And genes are the area of our genome where the instructions for constructing those proteins are stored.
For instance, the human genome has over 20,000 genes that code for proteins. It's interesting to note that just 1.5% of the complete human genome contains all of the information for those 20,000 protein-coding genes.
A broader definition of a gene includes DNA sequences, sometimes called RNA genes, that include instructions for building an RNA molecule that performs a function other than directly encoding a protein.
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Two identical pellet guns are fired simultaneously from the edge of a cliff. These guns impart an initial speed of 23.7 m/s to each pellet. Gun A is fired straight upward, with the pellet going up and then falling back down, eventually hitting the ground beneath the cliff. Gun B is fired straight downward. In the absence of air resistance, how long after pellet B hits the ground does pellet A hit the ground
Answer:
Ta - Tb = 4.84 sec (approx)
Explanation:
Time taken by A = Time taken By B + Extra time
Ta - Tb = T
We know that
Time (T) = [v-u] /a ...................[a=9.8 m/s²]
So,
Ta - Tb = [v-u] /a
Ta - Tb = [-23.7-23.7] /9.8
Ta - Tb = 4.8367 sec
Ta - Tb = 4.84 sec (approx)
Each insulated beaker contains equal amounts of the same fluid. The starting temperature of beaker A was 100.0 degrees Celsius and the starting temperature of beaker B was 0 degrees Celsius. At 5 minutes, the temperature of Beaker A was 82 and the temperature of Beaker B was 18. Assuming no heat was lost, what is the best estimate for the temperature of each beaker at 10 minutes?
Answer:
Correct Answer: B. Beaker A will be 72 °C and beaker B will be 28 °C.
This one is actually right!
You walk 20 m north then 30 m west for a total timer four minutes what is the magnitude of your average velocity in (m/s)
Answer:
The average velocity is 0.15 m/s
Explanation:
Use the definition of average velocity as the distance traveled divided the time it took.
Since the movement was on the plane from the origin (0, 0) to the point (-30, 20) corresponding to 30 m west and 20 m north, we calculate the distance using the distance between two points on the plane:
[tex]distance=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2} = \sqrt{(-30)^2+20^2} =\sqrt{1300} \approx 36.06\,\,m[/tex]
Then the magnitude of the average velocity can be estimated via the quotient between distance divided time, but since the units required are meters per second, we first convert the four minute time into seconds: 4 * 60 = 240 seconds.
Then the average velocity becomes:
[tex]v_{ave}=\frac{distance}{time} =\frac{36.06}{240} =0.15\,\,m/s[/tex]
In an emergency an airplane needs to land on a short runway at Albany County Airport. The plane comes in for a landing with a speed of 95 m/s. The planes maximum magnitude of acceleration is 7.07 m/s2 as it comes to a stop. (a) What is the minimum time interval needed for this plane to stop?
Answer:
t = 13.43 s
Explanation:
In order to find the minimum time required by the plane to stop, we will use the first equation of motion. The first equation of motion is written as follows:
Vf = Vi + at
where,
Vf = Final Velocity of the Plane = 0 m/s (Since, the plane finally stops)
Vi = Initial Velocity of the Plane = 95 m/s
a = deceleration of the plane = - 7.07 m/s²
t = minimum time interval needed to stop the plane = ?
Therefore,
0 m/s = 95 m/s + (- 7.07 m/s²)t
t = (95 m/s)/(7.07 m/s²)
t = 13.43 s
Use the exact values you enter to make later calculations. Jack and Jill are on two different floors of their high rise office building and looking out of their respective windows. Jack sees a flower pot go past his window ledge and Jill sees the same pot go past her window ledge a little while later. The time between the two observed events was 4.0 s. Assume air resistance is negligible. (a) If the speed of the pot as it passes Jill's window is 60.0 m/s, what was its speed when Jack saw it go by
The part B of the question is missing and it is;
b) What is the height between the two window ledges?
Answer:
A) 20.76 m/s
B) 161.52 m
Explanation:
A) To calculate the initial speed we use the formula from Newton's first law of motion:
v = u + at
Making u the subject gives;
u = v - at
Where;
v is the final velocity which is the speed when Jill sees the pot = 60 m/s
u is the initial velocity which is the speed when Jack sees the pot go by
t is the time between the two observed events = 4 s
a in this question is acceleration due to gravity = 9.81 m/s².
Plugging in the relevant values into the initial velocity equation gives;
u = 60 - (9.81 × 4)
u = 20.76 m/s
B) To get the height difference, we will use the formula;
(y1 - y0) = ut + ½at²
Thus, plugging in the relevant values, we have;
y1 - y0 = (20.76 × 4) + (½ × 9.81 × 4²)
(y1 - y0) = 161.52 m
An object accelerates at 20 m/s2. By how much does the speed change in one second?
Explanation:
a= v/t
v= at
= 20m/s2 × 1sec
= 20m/s
Describing Forms of Energy
Match each form of energy with its description.
nuclear energy
found when internal energy is
transferred
thermal energy
te
found in the nucleus of an atom
electrical energy
found in the flow of electrical charges
found in the bonds between atoms
chemical energy
Answer:
electrical energy-found in the flow of electrical charges
chemical energy-found in the bonds BTW atoms
thermal energy-found when internal energy is transferred
nuclear energy-found in the nucleus of an atom.
The correct match is: nuclear energy: found in the nucleus of an atom, thermal energy: found when internal energy is transferred, electrical energy: found in the flow of electrical charges, chemical energy: found in the bonds between atoms.
Nuclear energy: This type of energy is obtained from an atom's nucleus. It is released by processes such as nuclear fission or fusion, which utilise the energy held inside atomic nuclei.
Thermal energy is the energy associated with an object's or a system's temperature. When there is a temperature differential, it is a type of internal energy that is exchanged between objects.
Electrical energy is associated with the passage of electric charges, such as electrons, via a conductor.
Chemical energy is contained in the bonds that connect atoms and molecules. When these connections are broken or created, it is released or absorbed during chemical processes.
Thus, this can be the match for the given forms of energy.
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You walk 10 meters to class in 20 seconds , your average speed is ___ ?
The average speed is 1/2 m/s.
To determine the answer, we need to know about average speed.
What is average speed?Distance covered by an object per unit time is known as average speed.
What is the mathematical formula of average speed?Mathematically, average speed= Total distance travelled/ total time taken
What is the average speed, if I walk 10 metes in 20s?Here, total distance travelled = 10m,
total time taken = 20s
Average speed = 10/20 = 1/2 m/s
Thus, we can conclude that the average speed is 1/2 m/s.
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Summarize why psychology is considered a science.
because it uses a systematic method of asking and answering problems, and it attempts to develop solution to psychological problems.
Answer:
it uses a systematic method of asking and answering problems,
Explanation:
A Van de Graaff generator is charged so that a proton at its surface accelerates radially outward at 1.35 ✕ 1012 m/s2. Find the following. (a) the magnitude of the electric force on the proton at that instant magnitude N direction ---Select--- (b) the magnitude and direction of the electric field at the surface of the generator magnitude N/C direction ---Select---
Answer:
(a).
We know that force is
F = m a
So
F = (1.67 x 10^(-27) x (1.38 x10^12)
F = 2.3 x 10^-15 N facing the radially outward direction
(b).
Similarly Force for charge is
F = q E = m a
So relating
E = F/q = 2.3x 10^-15 /(1.6 10^ -19
E = 144.75 N/C facing the radially outward direction
The answer to the question is
(a) The force on the proton is [tex]2.254\times10^{-15}\,N[/tex] directed radially outwards.
(b) The electric field at the surface of the generator is [tex]14031.25\, N/C[/tex] directed radially outwards.
The answer can be explained as shown below.
Given that a proton accelerates radially outward at [tex]1.35\times 10^{12}\,m/s^2[/tex].
ie; [tex]a=1.35\times 10^{12}\,m/s^2[/tex]We know the mass of a proton, [tex]m_p = 1.67\times10^{-27}\,kg[/tex].From Newton's second law we have,
[tex]F=mg[/tex]But here, [tex]m=m_p[/tex]
So, the electric force on the proton is;
[tex]F = m_p\, a= (1.67\times10^{-27}\,kg)\, \times(1.35\times 10^{12}\, m/s^2)=2.254\times10^{-15}\,N[/tex]The force on the proton is [tex]2.254\times10^{-15}\,N[/tex] directed radially outwards.Also, we know that, in electrostatics,
[tex]F=Eq\\ \\\implies E=\frac{F}{q}[/tex]The charge of a proton is, [tex]q=1.6\times 10^{-19}\,C[/tex]Therefore, the electric field is given by,
[tex]E=\frac{2.254\times 10^{-15}N}{1.6\times 10^{-19}\,C} = 14031.25\, N/C[/tex]The electric field at the surface of the generator is [tex]14031.25\, N/C[/tex] directed radially outwards.Learn more about the electric force here:
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A stone is thrown vertically downward with an initial speed of 12.0 m/s from the top of a
building. The stone takes 1.54 s to reach the ground.
The question is incomplete; However, the height from which the stone is thrown is most likely to be what's required of the question
Answer:
See Explanation
Explanation:
Given
[tex]Initial\ Speed, u = 12.0m/s[/tex]
[tex]Time, t = 1.54\ s[/tex]
Required
Determine the height
This question will be answered using the following equation of motion;
[tex]S = ut + \frac{1}{2}gt^2[/tex]
Take g as 9.8
This gives:
[tex]S = 12 * 1.54 + \frac{1}{2} * 9.8 * 1.54^2[/tex]
[tex]S = 12 * 1.54 + \frac{1}{2} * 9.8 * 2.3716[/tex]
[tex]S = 18.48 + 11.62084[/tex]
[tex]S = 30.10084[/tex]
[tex]S = 30.1\ m[/tex] (Approximated)
Hence; Height = 30.1m
seagull is flying at a rate of 20 miles per hour south, it encounters wind blowing 20 miles per hour north. What is the resultants
Answer:
the winds will make the bird stop
Explanation:
is basically 20 - 20
At a time of 30 seconds a runner passes a distance marker labeled "125 meters." If the velocity of the runner is +5.0 m/s, when did the runner pass the distance marker for 75 meters?
Answer:
Explanation
He runs at 5m/s, so in 30 s he should be at 150m. So you have to do 125m - 150m and you'll get -25m, this is his initial position. They want to know the time when he hits 75m, so you would do 75 + 25, and get 100. Then do 100m / 5m/s, and you will get 25 seconds.
An electron enters a region of uniform electric field with an initial velocity of 64 km/s in the same direction as the electric field, which has magnitude E = 48 N/C. (a) What is the speed of the electron 1.3 ns after entering this region? (b) How far does the electron travel during the 1.3 ns interval?
Answer:
1.) 11 km/s
2.) 9.03 × 10^-5 metres
Explanation:
Given that an electron enters a region of uniform electric field with an initial velocity of 64 km/s in the same direction as the electric field, which has magnitude E = 48 N/C.
Electron q = 1.6×10^-19 C
Electron mass = 9.11×10^-31 Kg
(a) What is the speed of the electron 1.3 ns after entering this region?
E = F/q
F = Eq
Ma = Eq
M × V/t = Eq
Substitute all the parameters into the formula
9.11×10^-31 × V/1.3×10^-9 = 48 × 1.6×10^-19
V = 7.68×10^-18 /7.0×10^-22
V = 10971.43 m/s
V = 11 Km/s approximately
(b) How far does the electron travel during the 1.3 ns interval?
The initial velocity U = 64 km/s
S = ut + 1/2at^2
S = 64000×1.3×10^-6 + 1/2 × 8.4×10^12 × ( 1.3×10^-9)^2
S =8.32×10^-5 + 7.13×10^-6
S = 9.03 × 10^-5 metres
Write the following numbers in proper scientific notation:
1.) 36513
2.) 0.00050
3.) 8004
4.) 0.00000000406
Answer:
0.00050, 0.000000000406, 36513
A classroom is about 3 meters high, 20 meters wide and 30 meters long. If the density of air is 1.29 kg/m3, what is the mass of the air in the classroom?
Answer:
the mass of the air in the classroom = 2322 kg
Explanation:
given:
A classroom is about 3 meters high, 20 meters wide and 30 meters long.
If the density of air is 1.29 kg/m3
find:
what is the mass of the air in the classroom?
density = mass / volume
where mass (m) = 1.29 kg/m³
volume = 3m x 20m x 30m = 1800 m³
plugin values into the formula
1.29 kg/m³ = mass
1800 m³
mass = 1.29 kg/m³ ( 1800 m³ )
mass = 2322 kg
therefore,
the mass of the air in the classroom = 2322 kg
If A classroom is about 3 meters high, 20 meters wide and 30 meters long. If the density of air is 1.29 kg/m3, then the mass of the air in the classroom is 2322Kg.
What is density??Density is the ratio of mass to volume. it tells how much mass a body is having for its unit volume. for example egg yolk has 1027kg/m³ of density, means if we collect numbers of egg yolk and keep it in a container having volume 1 m³ then total amount of mass it is having will be 1027kg. Density is a scalar quantity. when we add egg yolk into the water, egg yolk has greater density than water( 997 kg/m³), because of higher density of egg yolk it contains higher mass in same volume as water. hence due to higher mass higher gravitational force is acting on the egg yolk therefore it goes down on the inside the water. water will float upon the egg yolk. same situation we have seen when we spread oil in the water. ( in that case water has higher density than oil. thats why oil floats on the water).
Given,
Height = 3 m
Width = 20 m
length= 30 m
Density of air = 1.29kg/m³
The volume of the room = 3×20×30 m³
Volume V = 1800m³
By formula,
Density = Mass/Volume
1.29kg/m³ = Mass/1800m³
Mass of the air = 1.29×1800 = 2322 Kg
The mass of the air is classroom is 2322Kg.
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why Newtown made the laws of motion
Answer:Newton’s law also states that larger bodies with heavier masses exert more gravitational pull, which is why those who walked on the much smaller moon experienced a sense of weightlessness, as it had a smaller gravitational pull. To help explain his theories of gravity and motion, Newton helped create a new, specialized form of mathematics.
Explanation:
Answer:
Newton was convinced the planets must obey the same physical laws that are observed on Earth. This meant there must be an unseen force acting on them. He knew from experiment that, in the absence of an applied force, a moving body will continue in a straight line forever.
Explanation:
Which statement supports Newton’s first law of motion?
Answer:
Newton's first law of motion is that an object at rest will stay at rest, unless acted upon by an external force.
--------------------------------------------------------------------------------------------------------------
The "external force" can be anything, from a gust of wind, to a person moving the object. His first law also corresponds with the definition of inertia.
Hope this helps!
Q1. My brakes stop me at -5.5m/s^2 when I lock them up. A puppy runs in front of my car, and I stop just in time 3.5 seconds later. How far did I skid? Q2. I floor the pedal and accelerate from 7.0m/s to 35m/s over a fouth of a mile (0.40km). What is my accelleration?
please explain step by step, much thanks :)
Explanation:
Q1. Given:
v = 0 m/s
a = -5.5 m/s²
t = 3.5 s
Find: Δx
Δx = vt − ½ at²
Δx = (0 m/s) (3.5 s) − ½ (-5.5 m/s²) (3.5 s)²
Δx ≈ 33.7 m
Q2. Given:
Δx = 400 m
v₀ = 7.0 m/s
v = 35 m/s
Find: a
v² = v₀² + 2aΔx
(35 m/s)² = (7.0 m/s)² + 2a (400 m)
a = 1.47 m/s²
What potential difference is required to produce a current of 0.5 A in a bulb of power 60 W
Answer:
ans is 120
Explanation:
I= 0.5 A
p= 60w
p=Iv
60/0.5
v= 120
Answer:
V=P/I
V=60/0.5
V=120
Explanaton:
the formula P=IV is converted to V=P/I to make V (voltage) the subject. then sub in the values to get your answer
note that potential difference is same as voltage
A tugboat tows a ship at a constant velocity. The tow harness consists of a single tow cable attached to the tugboat at point A that splits at point B and attaches to the ship at points C and D. The two rope segments BC and BD angle away from the center of the ship at angles of ϕ = 26.0 ∘ and θ = 21.0 ∘, respectively. The tugboat pulls with a force of 1200 lb . What are the tensions TBC and TBD in the rope segments BC and BD?
Answer:
The tensions in [tex]T_{BC}[/tex] is approximately 4,934.2 lb and the tension in [tex]T_{BD}[/tex] is approximately 6,035.7 lb
Explanation:
The given information are;
The angle formed by the two rope segments are;
The angle, Φ, formed by rope segment BC with the line AB extended to the center (midpoint) of the ship = 26.0°
The angle, θ, formed by rope segment BD with the line AB extended to the center (midpoint) of the ship = 21.0°
Therefore, we have;
The tension in rope segment BC = [tex]T_{BC}[/tex]
The tension in rope segment BD = [tex]T_{BD}[/tex]
The tension in rope segment AB = [tex]T_{AB}[/tex] = Pulling force of tugboat = 1200 lb
By resolution of forces acting along the line A_F gives;
[tex]T_{BC}[/tex] × cos(26.0°) + [tex]T_{BD}[/tex] × cos(21.0°) = [tex]T_{AB}[/tex] = 1200 lb
[tex]T_{BC}[/tex] × cos(26.0°) + [tex]T_{BD}[/tex] × cos(21.0°) = 1200 lb............(1)
Similarly, we have for equilibrium, the sum of the forces acting perpendicular to tow cable = 0, therefore, we have;
[tex]T_{BC}[/tex] × sin(26.0°) + [tex]T_{BD}[/tex] × sin(21.0°) = 0...........................(2)
Which gives;
[tex]T_{BC}[/tex] × sin(26.0°) = - [tex]T_{BD}[/tex] × sin(21.0°)
[tex]T_{BC}[/tex] = - [tex]T_{BD}[/tex] × sin(21.0°)/(sin(26.0°)) ≈ - [tex]T_{BD}[/tex] × 0.8175
Substituting the value of, [tex]T_{BC}[/tex], in equation (1), gives;
- [tex]T_{BD}[/tex] × 0.8175 × cos(26.0°) + [tex]T_{BD}[/tex] × cos(21.0°) = 1200 lb
- [tex]T_{BD}[/tex] × 0.7348 + [tex]T_{BD}[/tex] ×0.9336 = 1200 lb
[tex]T_{BD}[/tex] ×0.1988 = 1200 lb
[tex]T_{BD}[/tex] ≈ 1200 lb/0.1988 = 6,035.6938 lb
[tex]T_{BD}[/tex] ≈ 6,035.6938 lb
[tex]T_{BC}[/tex] ≈ - [tex]T_{BD}[/tex] × 0.8175 = 6,035.6938 × 0.8175 = -4934.1733 lb
[tex]T_{BC}[/tex] ≈ -4934.1733 lb
From which we have;
The tensions in [tex]T_{BC}[/tex] ≈ -4934.2 lb and [tex]T_{BD}[/tex] ≈ 6,035.7 lb.
A ball rolls off a 1.0 m high table and lands on the floor 3.0 m away from the table. a. How long is the ball in the air?
Answer:
The ball is in the air for approximately 0.45 seconds
Explanation:
We only need to use the information on the height of the table to find the time, since the vertical movement is a movement under the acceleration of gravity, and with no initial velocity in the y-direction (recall that the ball rolls off a 1.0 m high table)
therefore the equation of motion for the vertical component is:
[tex]y_f-y_i=\frac{1}{2}\, g\,t^2[/tex]
which for our information becomes:
[tex]y_f-y_i=\frac{1}{2}\, g\,t^2\\1 = 4.9\,t^2\\t^2=\frac{1}{4.9} \\t=\sqrt{\frac{1}{4.9}} \\t\approx 0.45\,s[/tex]