The coefficient of dynamic friction between the grass and a 200 kg football blocking sled is 0.20. If a football player only pushes horizontally against the sled, how large must the horizontal force be to keep the sled moving at constant velocity
The horizontal force be to keep the sled moving at constant velocity is 392 N.
Horizontal force applied to the sled
The horizontal force applied to the sled to prevent it from moving is calculated from Newton's second law of motion.
F - Ff = ma
where;
a is acceleration of the sledat constant velocity, a = 0
F - μmg = m(0)
F - μmg = 0
F = μmg
F = 0.2 x 200 x 9.8
F = 392 N
Thus, the horizontal force be to keep the sled moving at constant velocity is 392 N.
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A bag of frozen vegetables expanding in the microwave is a good example of how volume __________.
A. increases when temperature decreases
B. decreases when temperature increases
C. decreases when temperature decreases
D. increases when temperature increases
Answer:
D
Explanation:
because when the temperature increases things tend to rise and explode instead of decreasing
DOES THE SUN CONTAIN NUCLEAR ENERGY?
Answer: yes
Explanation: it's fueled by nuclear reactions that fuse hydrogen atoms together into helium and other heavier elements, releasing huge amounts of energy in the process.
After reading the passage about acupuncture, identify which scientific claim explains why some people say acupuncture does not truly relieve pain.
Answer:
The answer would be "This ancient form of pain relief and stimulation is said to benefit patients by blocking channels which practitioners claim
Explanation:
Answer:
It provides only a placebo effect.
Explanation:
Edge
When a ball rolls along the carpet, it slows down faster than when it is rolled on the floor. What transfer of energy explains this observation?
Answer:
D.) A carpet transfers more energy to heat than the floor.
The frictional force between carpet and ball is more due to the rough surface of the carpet as compared to the friction between floor and ball, so the ball on the carpet would come to rest first before a ball on the floor.
Explanation:
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what is the wavelength of a 28Hz periodic wave at 10 meters per second?
AnswerAnswerAnswerAnswerAnswer:0.3571m
Explanation:
what is the difference between reflection and refraction? What changes and what does not change.
Answer:
Reflection involves a change in direction of waves when they bounce off a barrier. Refraction of waves involves a change in the direction of waves as they pass from one medium to another.
Explanation:
Question 12 A wave has a wavelength of 7.96 m and travels at 30.67 m/s. What is the frequency of the wave?
Answer:
0.2597hertz
Explanation:
first of all we have to calculate time.
time is given by speed/distance
hence=30.67/7.96
=3.85s
frequency is given by 1/time
=1/3.85
=0.2597hertz
Question 1
A bus travels 5 km east. Then it travels 3 km west by the same path and stops.
What is the bus's displacement?
O 10 km
O2 km
O3km
O 8 km
What happens when oxygen comes in contact with NOx and VOCs?
1. They combine to create ozone to replenish the ozone layer.
2. Oxygen neutralizes NOx and VOCs.
3. They combine to form low altitude ozone.
4. They combine to form smog.
When oxygen comes in contact with NOx and VOCs They combine to create ozone to replenish the ozone layer. Option A is correct.
What is an ozone layer?The layer form on the stratosphere region of the earth, which absorbs most of the ultraviolet rays.
The ultraviolet rays come from the sun are very harmful, increases global warming when enter inside the ozone layer due to its deplection.
When oxygen comes in contact with NOx and VOCs They combine to create ozone to replenish the ozone layer.
Hence, option A is correct.
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Any sound with a frequency that is too low for humans to hear is called:
Answer:
infrasound
Explanation:
What happens when a sound wave passes by the particles of a medium?
Answer:
Propagation of Sound Waves:
Sound waves move (propagate) through a medium by means of particle-to-particle interaction. The source disturbs the immediately surrounding particles, causing them to vibrate about their fixed position at the same frequency as the source.
Inboard gasoline boats built after july 31st, 1981 must have what type of ventilation system?.
Inboard gasoline boats built after July 31st, 1981 must have a mechanical type of ventilation system.
What is a mechanical ventilation system?A mechanical ventilation system can be defined as a device in which circulates fresh/cold currents of air.
A mechanical ventilation system is based on the use of systems of ducts capable of ventilating the device.
In conclusion, inboard gasoline boats built after July 31st, 1981 must have a mechanical type of ventilation system.
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Mr. Ramirez demonstrates that objects can exert forces on each other even when the objects
are not touching. He removes two long pleces of clear plastic tape from a tape dispenser. He
holds a piece of tape in each hand so that they are hanging down. As he moves his hands closer together, the pieces of tape repel each other. His students then plan an investigation to study the forces exerted by the pieces of tape. a. Identify two factors that may affect the forces exerted by the pieces of tape. Explain your
reasoning.
b. Describe how the effect of one of the factors you identified in part (a) could be tested. Be sure to include a description of how the effect would be measured and how the collected data would be analyzed.
The two factors that may affect the forces exerted by the pieces of tape are the charge on the tape and distance between them.
The effect of one of the factors could be tested by altering the distance and calculating the forces between them.
What is force?A force is the push or pull which make a body to move or stop it.
a. When two objects are kept apart. they are always attracted when uncharged kept at any distance.
When the objects are charged, the force will be attractive or repulsive.
The distance between those charged objects increase or decrease in strength depending on the distance between them.
Thus, the two factors that may affect the forces exerted by the pieces of tape are the magnitude of charge on the tape and distance between them.
b. By increasing the distance between the tapes, we can find the strength of forces.
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Warren is a professional triathlete when doing an
Ironman, Warren swims 3.86km in 45 mins, then
bikes for 180.5 km in 5 hours and finishes by
running a marathon 42.2km in 2.75 hours. What is
Warren's average speed in Km/hr and m/s
Answer:26.7 and 7.4
Explanation:
So, first you add all the time up then the area travelled.
Firstly; 45 mins + 300 minutes(5 hours) + 165 minutes(2.75 minutes)= 510 minutes
Secondly; 42.2KM + 180.5KM + 3.86KM= 226.56KM
Finally: For hourly you would do: 510 divided by 60 to get 510 mins in terms of hours: so, 8.5 hours then you would do 226.56KM divided by 8.5 hours to get: 26.7Km/hr
For m/s: 7.4m/s
What is the de Broglie wavelength of a 2.89 x 10-28 kg particle moving
at 3.00 x 108 m/s? (h = 6.626 x 10-34 J-s)
Explanation:
formula is given by
h/mv
where h is 6.626 × 10 ^-34
and c = 3 × 10^8
m = mass
by plugging in the values in the formula, the de Brogile wavelength is equal to 7.6424 × 10^(-15)
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50 points physics question (multiple choice) Will give brainliest!
There are two systems that contain only the fundamental frequency and they are the systems C and D.
What is fundamental frequency?The term fundamental frequency refers to the lowest frequency of a vibrating body. It does not include the overtones or the harmonics.
From the image shown in the question, there are two systems that contain only the fundamental frequency and they are the systems C and D.
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Question 7.
When can a mouse have the same momentum as an elephant?
د ن ه ه
A. when the mouse has a large velocity and the elephant has a small velocity
when the mouse has a small velocity and the elephant has a large velocity
a mouse cannot have the same momentum as an elephant
D. when they both have the same velocity
A mouse have the same momentum as an elephant when the mouse has a large velocity and the elephant has a small velocity. The correct option is A.
What is momentum?The momentum is the product of the mass of the object and its velocity.
Mouse has mass very less than the elephant. In order to make their momentum same, the velocity of the mouse must be greater than the elephant.
Mm x Vm = Me x Ve
A mouse have the same momentum as an elephant when the mouse has a large velocity and the elephant has a small velocity.
Thus, the correct option is A.
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A metal artifact with a mass of 814.0 lbs and a length of 6.25 ft is recovered from the Queen Anne's Revenge wreckage site. It is believed to be a cannon. Unfortunately, the base of the cannon was not recovered, so it is a perfectly symmetrical metal tube. The outer circumference is 23.9 inches and the inner diameter of the bore is 11.5 cm. In order to care for it properly, it must be determined what type of metal it is composed of. What is the artifacts density in g/cm3
Answer:
discovered as obisdan
Explanation:
me ginus brooo
3. The distance from a makeup mirror to C (the radius of curvature) is 70 cm. How far from the mirror
can a person be and still see an upright, magnified image?
The far point from the mirror can a person be and still see an upright, magnified image is focus i.e. 35cm from mirror.
What is radius of curvature?The mirror is made out of a sphere which has its radius called the radius of curvature.
The focal length f is half of the radius of curvature R of the lens.
Given the radius of curvature is 70cm, then focal length will be 70/2 = 35cm.
The makeup mirror is a concave mirror which forms real and upright images. The magnified images are obtained when the object is placed between focus and mirror.
Thus, the far point is focus i.e. 35cm from mirror.
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In a billiards game, one player hits the cue ball towards another ball. The cue ball has a mass of 0.1kg and hits the other ball with a velocity of 2m/s. If the collision is completely elastic and the cue ball travels with a velocity of 0.8m/s after the collision, what is the mass and velocity of the other ball?
Answer:
3/70 kg ≈ 0.04286 kg
2.8 m/s
Explanation:
In a perfectly elastic collision, the total momentum of the system is constant, and the difference in velocities changes sign.
We assume the other ball is at rest initially, and that the collision is "head-on." That is, final velocities are in the same direction as the initial velocity of the cue ball. We further assume no energy loss, and that the balls do not rotate.
__
initial momentumAssuming the ball being hit is initially at rest, it contributes no momentum to the system. The total momentum is ...
(0.1 kg)(2 m/s) = 0.2 kg·m/s
__
initial velocity differenceIf the cue ball has velocity v1 and the hit ball has velocity v2, the initial difference of velocities is ...
v1 -v2 = 2 m/s -0 m/s = 2 m/s
__
final velocity differenceAfter the collision, we must have ...
v1 -v2 = -2 m/s . . . . the velocity difference changes sign
v2 = v1 +2 m/s = 0.8 m/s +2 m/s
v2 = 2.8 m/s
The velocity of the other ball is 2.8 m/s after the collision.
__
mass of the other ballThe total momentum after the collision is the same as before, so we must have ...
m1·v1 +m2·v2 = initial momentum
(0.1 kg)(0.8 m/s) +(m2)(2.8 m/s) = 0.2 kg·m/s
m2 = (0.2 kg·m/s -0.08 kg·m/s)/(2.8 m/s) = (0.12/2.8) kg = 3/70 kg
The mass of the other ball is 3/70 ≈ 0.04286 kg.
The half-life of radium-226 is 1,600 years and the half-life of carbon-14 is 5,730 years. In 1-2 sentences, mathematically prove that the decay constant for radium-226 is larger than the decay constant for carbon-14.
The decay constant for radium-226 is larger than the decay constant for carbon-14 due to its obtained value.
What is the rate of decay?
The reduction in the number of radionuclides per unit time is the rate of decay.
The decay constant of the radium-226 is;
[tex]\lambda_1=\frac{ 16}{100}\times 266 \\\\ \lambda_1= -36.16[/tex]
The decay constant of the carbon-14 is;
[tex]\lambda_2=\frac{ -57.3}{100}\times 14 \\\\ \lambda_1= -802.2[/tex]
Hence, the decay constant for radium-226 is larger than the decay constant for carbon-14.
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Answer:
0.693/1600 > 0.693/5730
Explanation:
The decay constant is the reciprocal of the time it takes for the radioactivity to decline to about 36.8% of its original value. It is the value of k in the multiplier e^(-kt), which tells the fraction remaining after time t.
When compared to the half-life, h, the value of k is ...
k = 0.693/h . . . . . decay constant for half-life h
Effectively, the decay constant is proportional to the inverse of the half-life. The constant of proportionality is ln(2) ≈ 0.693.
__
decay constant for radium-226:
0.693/1600 ≈ 4.33×10^-4
decay constant for carbon-14:
0.693/5730 ≈ 1.21×10^-4
Since 4.33×10^-4 is greater than 1.21×10^-4, the decay constant of radium-226 is larger than that of carbon-14.
_____
Additional comment
Taking the reciprocal of a positive number reverses the ordering:
1600 < 5730
1/1600 > 1/5730
The half-life of radium-226 is less than that of carbon-14, so its decay constant will be larger.
A car travels for 2 hours at a speed of 55 km/h. calculate the distance traveled
This is a uniform rectilinear motion (MRU) exercise.
We get the data:
d = ?, v = 55 km/h, t = 2 hr
To calculate the distance, multiply the speed by the time.
d = v * t
d = 55km/h * 2hr = 110kmThe distance traveled is 110 km.
Calculate the frequency of a wave which goes through 10 cycles in 5 s
the amount of energy at the end of the system (output) is different from the starting energy (input). How does this not violate (break) the law of the conservation of energy. This question is based on solar and wind energy
Answer:
Because some of the energy escaped or was used.
Explanation:
2. why did adding layers of paper help prevent the egg from breaking open rather than one thick layer with the same number of sheets?
What type of waves do not require a medium to travel?.
Answer:
electromagnetic waves
Calculate the power if work is 9000 joules and time is 60 seconds
Answer:
150w
Explanation:
power = workdone/time
9000/60
150w
Which picture shows an example of no work being done? A man and a woman hold a child in the air by the child's hands. A man pushes a shopping cart down the aisle of a grocery store. A child holds the bar of a set of weights without moving. A woman pulls a rolling suitcase.
Answer:
A child holds the bar of a set of weights without moving I think
An object moves 4 meters north, then 3 meters east. What is the displacement of the object?
Answer:
5 meters
Explanation:
4 and 3 are legs of a right triangle with the hypotenuse = displacement
Use Pythagorean theorem
4 ^2 + 3^2 = (displacement)^2
displacement = 5 m
The displacement of the object that moved 4 meters north, then 3 meters east is 5 meters.
What is displacement?
Displacement is change in the position of an object. It can be described as the shortest distance between the initial and final position of an object.
The displacement of the object is calculated as follows;
d² = 4² + 3²
d² = 25
d = 5 m
Thus, the displacement of the object that moved 4 meters north, then 3 meters east is 5 meters.
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