what activities belong at the top of the physical activity pyramid
Answers
Answer: Cut down on watching tv, sitting down for more than 30 minutes at a time, and playing video games.
Explanation:
Related Questions
Why would you expect sodium (Na) to react strongly with chlorine?
Answers
Answer:
Na is a alkaline metal, it can very easy give an electron, and form positive ion. Cl is a very strong non-metal(halogen), and it is able to take electron, and form negative ion. Positive and negative ion can attract to each other and form ionic bond.
An injured monkey sits perched on a tree branch 9 m above the ground, while a wildlife veterinarian is kneeling down in the bushes 90.0 m away attempting to subdue the monkey with a tranquilizer gun. The vet knows that the moment the gun fires, the monkey will be frightened and fall down from the branch. At what angle up from the ground must the veterinarian aim the gun so that the tranquilizer dart will hit the falling monkey? Given the angle, what is minimum speed at which the tranquilizer dart must leave the gun to still hit the monkey?
Answers
Answer:
The hunter should aim directly at the perched monkey because the tranquilizer dart will fall away from the line sight at the same rate that the monkey falls from its perch.
Tan theta = 9 / 90 = .1 so theta = 5.71 deg
The time for the monkey to reach the ground is
t = (2 h / g)^1/2 = (18 / 9.8)^1/2 = 1.36 sec
So the horizontal speed of the dart must be at least
Vx = 90 m / 1.36 sec = 66.4 m/s
Vx = V cos theta
V = 66.4 m/s / cos 5.71 = 66.7 m/s
The angle of projection of the tranquilizer dart is 5.7⁰
The horizontal speed of the tranquilizer dart is 66.5 m/s
The given parameters;
vertical position of the monkey, y = 9 mhorizontal position of the veterinarian, x = 90The angle of projection of the tranquilizer dart is calculated as;
[tex]tan(\theta) = \frac{y}{x} \\\\tan(\theta) = \frac{9}{90} \\\\tan(\theta) = 0.1\\\\\theta = tan^{-1}(0.1)\\\\\theta = 5.71 ^0[/tex]
The speed of the tranquilizer dart is calculated as;
X = v₀ₓt
where;
t is the time to reach maximum height
X is the horizontal displacement = 90 m
The time to reach maximum height is calculated as;
[tex]h = v_0_yt + \frac{1}{2} gt^2\\\\h = 0 + \frac{1}{2} gt^2\\\\h = \frac{1}{2} gt^2\\\\t = \sqrt{\frac{2h}{g} } \\\\t = \sqrt{\frac{2\times 9}{9.8} } \\\\t = 1.36 \ s[/tex]
The horizontal speed of the tranquilizer dart is calculated as;
[tex]X = v_0cos(\theta) \times t\\\\90 = v_0\times cos(5.71) \times 1.36\\\\90 = 1.353 v_0\\\\v_0= \frac{90}{1.353} \\\\v_0 = 66.5 \ m/s[/tex]
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When describing image formation for plane mirrors, what is an important rule
to remember about light rays?
Answers
Answer: The image formed by a plane mirror is always virtual (meaning that the light rays do not come from the image), upright and of the same shape and size as the object it is reflecting.
Answer: B. The angle when it leaves is the same as the angle when it hits
Explanation:
Apex
potential energy is frequintly converted into kenetic energey. kenetic energey
Answers
Answer:
When an object falls, its gravitational potential energy is changed to kinetic energy. ... Gravitational potential energy for a mass m at height h near the surface of the Earth is mgh more than the potential energy would be at height 0. (It's up to you where you choose height 0.)
Explanation:
Answer:
Qwertyujiknb vcdxrftyhbvcdxrft6y7uij
Explanation:
A car starts from rest and attains a velocity of 30m/s in 5 sec . calculate the total distance travel by that car and acceleration
Answers
Answer:
Acceleration (a) = 6 m/s²
Total distance travel by car(s) = 75 meter
Explanation:
Given:
Initial velocity (u) = 0
Final velocity (v) = 30 m/s
Time (t) = 5 sec
Find:
Total distance travel by car(s) = ?
Acceleration (a) = ?
Computation:
v = u +at
30 = 0 + a(5)
30 = a(5)
Acceleration (a) = 6 m/s²
Total distance travel by car(s) = ut +1/2(a)(t)²
Total distance travel by car(s) = 1/2(a)(t)²
Total distance travel by car(s) = (0.5)(6)(5)²
Total distance travel by car(s) = 75 meter
People often think that Galileo dropped two objects of dramatically different mass off of the Leaning Tower of Pisa that both hit the ground at the same time. Explain why in reality this was most likely not true.
Answers
Answer: because of air resistance. See explanation for further details.
Explanation: Galileo performed an experiment to proof that the time of descent of two different masses is independent of time.
But in reality this is most likely not true because of air resistance and other fluid frictional effects in consideration.
If the experiment is performed in a vacuum, it will always be true that time is independent of masses of two falling objects.
A train is moving west with an initial velocity of 20m/s accelerates at 4m/s for 10 seconds during this time the train moves a distance
Answers
Answer:
400m
Explanation:
From Newton's law of motion;
S = ut + 1/2 at2
Where U is initial velocity
a is acceleration
t is velocity hence;
S is distance covered
S = 20×10 + 1/2 × 4×(10)^2
= 200 + 200 = 400m
A 1380 kg car starts from rest at the top of a 28.0 m long hill inclined at 11.00 degrees. Ignoring friction, how fast is it going when it reaches the bottom of the hill?
Answers
Answer:
10.2 m/s
Explanation:
Using conservation of energy:
PE = KE
mgh = ½ mv²
v = √(2gh)
v = √(2 × 9.8 m/s² × 28.0 m × sin 11.0°)
v = 10.2 m/s
The velocity when car reaches the bottom of the hill is 10.2 m/s.
What is mechanical energy?The mechanical energy is the sum of kinetic energy and the potential energy of an object at any instant of time.
M.E = KE +PE
M.E = ½ mv² + mgh
where g is the acceleration due to gravity, v is the velocity, m is the mass and h is the height of the object.
Given is a 1380 kg car starts from rest at the top of a 28.0 m long hill inclined at 11.00 degrees.
Using conservation of energy principle, we have
PE = KE
mgh = ½ mv²
v = √(2gh)
Substitute the values, we get
v = √(2 × 9.8 m/s² × 28.0 m × sin 11.0°)
v = 10.2 m/s
Thus, the velocity when car reaches the bottom of the hill is 10.2 m/s.
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Which of the following characterizes the particles in this diagram?
A. Two positive charges
B. One positive charge and one negative charge
C. Two negative charges
D. Two neutral charges
Answers
Answer:
B
Explanation:
One positive charger and one negative charger
why is no one helping?
Answers
Answer:
First one is hyperopia, second is myopia
Explanation:
Hyperopia is when the image is formed behind the retina.
Myopia is when images are formed infront of the retina.
a 1000 kg rhinoceros running at its top speed of 15 m/s has a kinetic energy of a.bc X 10^ J. What are the values of a.b.c. and d?
Answers
Answer:
K.E = 1.13 × 10^5 J
When compared to;
K.E = a.bc X 10^d J
We can observe that;
a = 1
b = 1
c = 3
d = 5
Explanation:
Given;
Mass of rhinoceros m = 1000kg
Velocity v = 15m/s
The kinetic energy of the body at this speed is;
K.E = 0.5×mv^2 ........1
Substituting the values of m and v into equation 1;
K.E = 0.5×1000×15^2
K.E = 112500 J
K.E = 1.13 × 10^5 J
When compared to;
K.E = a.bc X 10^d J
We can observe that;
a = 1
b = 1
c = 3
d = 5
The graph shows the motion of a cyclist.
Calculate;
a) The acceleration in the first 20 s.
b) The acceleration between 20 and 30s.
c) The acceleration in the last 10 s.
d) The distance travelled by the cyclist when he was moving at a constant speed?
Show working.
Answers
Answer:
A. 0.5m/s².
B. –0.5m/s².
C. –0.5m/s².
D. 100m.
Explanation:
A. Determination of the acceleration in the first 20s.
Initial velocity (u) = 0
Final Velocity (v) = 10m/s
Time (t) = 20secs.
Acceleration (a) =..?
Acceleration = change in Velocity /time
a = (v – u)/t
a = (10 – 0)/20 = 10/20
a = 0.5m/s²
Therefore, the acceleration of the cyclist in the first 20secs is 0.5m/s²
B. Determination of the acceleration between 20 and 30s. This can be obtained as follow:
Initial velocity (u) = 10m/s
Final Velocity (v) = 5m/s
Time (t) = 30 – 20 = 10s
Acceleration (a) =..?
Acceleration = change in Velocity /time
a = (v – u)/t
a = (5 – 10)/10 = –5/10
a = –0.5m/s²
Therefore, the acceleration of the cyclist between the 20 and 30secs is
–0.5m/s².
C. Determination of the acceleration in the last 10s.
Initial velocity (u) = 5m/s
Final Velocity (v) = 0
Time (t) = 10s
Acceleration (a) =..?
Acceleration = change in Velocity /time
a = (v – u)/t
a = (0 – 5)/10 = –5/10
a = –0.5m/s²
Therefore, the acceleration of the cyclist between the last 10secs is
–0.5m/s².
D. Determination of the distance travelled by the cyclist when he was moving at a constant speed.
Velocity (v) = 5m/s
Time (t) = 50 – 30 = 20secs
Displacement (d) =?
Velocity = Displacement /Time
v = d/t
5 = d/20
Cross multiply
d = 5 x 20
d = 100m
Therefore, the distance travelled by the cyclist at constant speed is 100m
At what wavelength would a star radiate the greatest amount of energy if the star has a surface temperature of 60,000 K?
Answers
Answer:
[tex]\lambda=4.81\times 10^{-8}\ m[/tex]
Explanation:
We have,
The surface temperature of the star is 60,000 K
It is required to find the wavelength of a star that radiated greatest amount of energy. Wein's displacement law gives the relation between wavelength and temperature such that :
[tex]\lambda T=2.89\times 10^{-3}[/tex]
Here,
[tex]\lambda[/tex] = wavelength
[tex]\lambda=\dfrac{2.89\times 10^{-3}}{60000}\\\\\lambda=4.81\times 10^{-8}\ m[/tex]
So, the wavelength of the star is [tex]4.81\times 10^{-8}\ m[/tex].
suppose that g (x) equals f (x + 1) - 3 which statement best compares the graph of g (x) with the graph of f (x)
Answers
Answer:
The graph of G(x) is the graph of F(x) shifted 1 unit to the left and 3 units down.
Explanation:
f(x + q) which is left q units
f(x - q) which is right q units
f(x) + q which is up q units
f(x) - q which down q nits
and
G(x) = F(x + 1) - 3
So,
f(x + 1) shifts to left 1 unit
f(x) - 3 shifts to down 3 units
So, the correct answer is B.
The graph of G(x) is the graph of F(x) shifted 1 unit to the left and 3 units down.
A wire having resistance 20 ohm is bent to make a closed square.What is the resistance across the diagonal of square?
Answers
Answer:
5 Ω
Explanation:
When it is bent into a square, each side of the square will get 5 Ω resistance. As considered diagonally ,path of the wire between to diagonal points is the two sides of the square (that is half the length of the wire connected in parallel position). Which gives 10 ohm parallel to 10 ohm wire. So it finally read as 5 Ω wire
Just need the answer to D please
Answers
The boat has to pull with MORE force. Don't forget about the force of friction with the water, pulling the skier in the backwards direction. The force that accelerates him is the NET force ... boat force minus water resistance. So the boat force has to be greater than the net accelerating force.
In some creatures, bioluminescence transforms
energy
energy into
OA) heat; light
OB) light; heat
OC) chemical potential; light
OD) light; chemical potential
Answers
Answer:
Hey!
Your answer would be option B. Light; heat...
Explanation:
In bioluminescent organisms, the energy is transformed int light energy and less then 20% of the total energy is put into Thermal Radiation!
HOPE THIS HELPS!!
b) Explain the method of preparing electromagnet. How do you test the
poles of an electromagnet with the help of magnetic compass ?
Answers
Answer:
An electromagnet is made by forming a coil around a soft iron bar (known here as the metal) such as a nail or screw and connect with an insulated copper wire (known here as the electric current conductor) the ends of the wound copper is then connected separately to the positive and negative terminals of a battery (known here as the source of electric current)
The north seeking needle of the magnetic compass will move away when brought close to the north pole of the formed electromagnet which can then be labelled N
The magnetic compass needle will be attracted to the south pole of the electromagnet which can then be labelled S
Explanation:
An electromagnet is an electric powered magnet that is formed (temporarily) by the perpendicular movement of electric current with respect to a metal core
The magnitude and the poles of an electromagnet can be changed by changing the magnitude and the direction of flow of the electric current respectively.
The amplitude of a particle executing simple harmonic motion is 5cm, while its angular velocity is 10 rads -1 . Calculate the magnitude of the maximum acceleration of the particle.
Answers
Answer:
a_max = 50 cm/s^2
Explanation:
To find the magnitude of the maximum acceleration of the particle, you take into account the equation of motion in a simple harmonic motion:
[tex]x=Acos(\omega t)[/tex]
ω: angular velocity = 10 rad/s
A: amplitude = 5 cm
The acceleration is given by:
[tex]a=\omega^2 x[/tex]
and the maximum acceleration is obtained when the cosine function is maximum, that is, when cos(wt) = 1. Then, you have:
[tex]a_{max}=\omega^2 x_{max}=\omega^2A[/tex]
Then, you replace the values of w and A in order to calculate a_max:
[tex]a_{max}=(10rad/s)^2(5cm)=50\frac{cm}{s^2}[/tex]
hence, the maximum acceleration is 50 cm/s^2
A 50 - N x m torque acts on a wheel with a moment of inertia 150 kg x m² . If the wheel starts from rest , how long will it take the wheel to make one revolution ?
Answers
Answer:
t = 6.17 s
Explanation:
For a 1 revolution movement, [tex]\triangle \theta = 2\pi[/tex]
Torque, [tex]\tau = 50 Nm[/tex]
Moment of Inertia, [tex]I = 150 kg m^2[/tex]
If the wheel starts from rest, [tex]w_{0} = 0 rad/s[/tex]
The angular displacement of the wheel can be given by the formula:
[tex]\triangle \theta = \omega_0 t + 0.5 \alpha t^2[/tex]................(1)
Where [tex]\alpha[/tex] is the angular acceleration
[tex]\tau = I \alpha\\\alpha = \frac{\tau}{I} \\\alpha = 50/150\\\alpha = 0.33 rad/s^2[/tex]
To get t, put all necessary parameters into equation (1)
[tex]2\pi = 0(t) + 0.5(0.33)t^2\\2\pi =0.5(0.33)t^2\\t^2 = \frac{4 \pi}{0.33} \\t^2 = 38.08\\t = 6.17 s[/tex]
A car accelerates from 10m/s to 20m/s over a distance of 80m. What is its acceleration?
Answers
Answer:
0.125m/s^2
Explanation:
20-10=10
10 divided by 80=0.125m/s^2
The average velocity of the car is 15 m/s. The time taken to travel over the distance with this velocity is 5.3 seconds. Then the acceleration of the car is 1.8 m/s².
Wat is acceleration ?Acceleration is a physical quantity measuring the rate of change in velocity of a moving object. Like velocity, acceleration is a vector quantity having magnitude and direction.
Acceleration is the ratio of change in velocity to the change in time.
a = Δv/Δt
Given, the car is accelerating from 10 to 20 m/s. Hence, it travelled with average velocity of 15 m/s over the distance of 80 m.
Then , time taken = distance/velocity
t = 80 m/15 m/s = 5.3 s
Acceleration = Δv/t = (20 -10 m/s) /5.3 s = 1.8 m/s².
Therefore, the acceleration of the car is about 1.8 m/s².
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Differents between foundamental quantity and derived quantities
Answers
Answer:
fundamental quantity can simply be defined as an independent quantity while derived quantity is dependent i.e. the derive their quantities from the fundamental
You apply a force of 54 N to a car jack in order to change a tire. Each "Crank" of the jack is exerted over a distance of
64 cm. What is the work input on the car jack? (Hint: 1m = 100 cm)
Step # 1
Step #2
Step #3
Answers
Explanation:
Work = force × distance
W = (54 N) (0.64 m)
W ≈ 35 J
HELLO ONCE MORE FRIENDS . PLEASE HELP ME.
Q.18) In the figure below, Force (F) of 2000 N is acting on the piston A and a bus is on the piston B. If the area of piston A is 50 cm2 and the area of piston B is 4000 cm2
a)Find the pressure produce of the piston B . (3 marks)
b)Find the weight of the bus on the poston B. ( 3 marks)
c)Calculate the mass of the bus. ( 3 marks)
Answers
Answer:
Do u want to talk?
Explanation:
Answer:
You found answer yet?
Explanation:
You get in your car to drive to school at 7:33 am and drive 10 miles north at a constant speed until 7:45
am, when you realize you left your homework on the kitchen table. You turn around and drive 10 miles
south back to your house and retrieve your homework at 8:00 am. You get back in the car and drive 15
miles north to school at a constant speed arriving at school at 8:29 am sharp, just in time to make it
before the bell rings.
e
Answers
Answer:
5.) 16.8 m/s
6.) 16.1 mph
7.) Moving fast.
Explanation:
5.) From the question, the total time will be:
7:33 am to 7:45 am = 12 minutes
As the car turns around,
7 : 45 am to 8 : 00am = 15 minutes
As you get back in the car and drive 15
miles north to school at a constant speed arriving at school at 8:29 am
8:00am to 8:29 am = 29 minutes
Total time = 12 + 15 + 29 = 56 minutes
Convert the minutes to second by multiplying the result by 60
Total time = 56 × 60 = 3360 seconds
Total distance covered will be
10 miles + 10 miles + 15 miles = 35 miles
Convert mile to meter by multiplying the result by 1609.344
35 × 1609.344 = 56327.04
Speed is a scale quantity. It only involves magnitude but no direction.
Average speed = total distance/total time
Average speed = 56327.04/3360
Average speed = 16.764 m/s
6.) Velocity = displacement/time
Velocity is a vector quantity. We will consider both the magnitude and direction
Total displacement = 10 miles - 10 miles + 15 miles = 15 miles.
Total time = 56 minutes
Convert minutes to hours by dividing it by 60
Total time = 56/60 = 0.93 hours
Substitute the time and displacement into the formula
Velocity = 15/0.93 = 16.07 mph
7.) . If you looked at your speedometer on your drive to school and it read 30mph, this value describes you move with a fast speed.
A ball hits a wall horizontally at 6m/s and rebounces at 4.4m/s the ball is in contact with wall for 0.04 sec. what is the acceleration.
Answers
Answer:
Acceleration (a) = 40 m/s²
Explanation:
Given:
Initial velocity (u) = 6 m/s
Final velocity (v) = 4.4 m/s
Time taken (t) = 0.04sec
Find:
Acceleration (a) = ?
Computation:
We know that,
⇒ v = u + at
⇒ a = (v - u) / t
⇒ Acceleration (a) = (4.4 - 6) / 0.04
⇒ Acceleration (a) = (-1.6) / 0.04
Acceleration (a) = 40 m/s²
I NEED ANSWER RN OR ILL BE DED
Answers
Answer:
i) O m/s² as velocity is constant
ii) 20m/s
iii)Hint:Calculate the area of the graph,that is;below the line, for the first 15 seconds only
Hope this helps.
A horse runs for 15 seconds to the south at a speed of 12 m/s. What is the
displacement of the horse in this time?
A. 180 m south
B. 150 m south
C. 150 m
D. 180 m
Answers
Answer: 180 m south
Explanation:
The displacement of the horse in this time is 180 m south. The correct option is A.
What is displacement?The displacement is the shortest distance travelled by the particle. It is the vector quantity which re[presents both the magnitude and direction.
Velocity is the time rate of change of displacement with time.
Given is a horse runs for 15 seconds to the south at a speed of 12 m/s. So, the displacement is
Displacement = Speed x Time
Put the values, we get
Displacement = 12 m/s x 15s
= 180 m
Thus, the displacement of the horse in this time is 180 m south.
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Which quantity Has the same unit as potential difference
Answers
Answer:
Voltage.
Explanation:
What is the compound name for Srl2
Answers
Answer:
i have no idea
Explanation:
im am quite sorry
The compound name for SrI₂ is strontium iodide.
A compound is a substance formed when two or more elements chemically combine together. It is composed of atoms of different elements that are held together by chemical bonds. Compounds have unique chemical and physical properties that are different from the elements they are made of.
Strontium iodide is an ionic compound consisting of strontium cations (Sr2+) and iodide anions (I-). When strontium (Sr) and iodine (I) react, they undergo a chemical reaction to form SrI₂.
Therefore, The name of the compound SrI₂ is strontium iodide.
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