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NemiM [27]
3 years ago
12

An arrow is fired directly upwards at 15m/s from the ground level.

Physics
1 answer:
erastova [34]3 years ago
3 0

Given that,

Initial Velocity, Vi = 15 m/s

acceleration due to gravity , g = 9.81 m/s²

Time in air, t = ?

Height, h = ?

Speed before striking ground, Vf = ?

Since, we know that,

2as = Vf² - Vi²

2*(-9.81)*s = 0 - 15²

solving above equation we have,

s= 11.46 m

or

h= 11.46 m

Height achieve by arrow will be 11.46 m

Since,

s = Vt

t= s/ V

t = 11.46/ 15

t = 0.76

Total time in air = 2 * t = 2*0.76

Time in air will be 1.53 s

Since,

2as = Vf² - Vi²

2*9.81* 11.46 = Vf² - 0

solving above equation we have,

Vf = 14.99 m/s

or

Velocity of arrow just before striking ground will be 15 m/s approximately.

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zzz [600]

(a) 10 GHz is the frequency of microwave radiation.

(b) 0.167 ms is required by the microwave to travel between two mountains.

Answer:

Explanation:

(a). 1 MHz is the frequency of microwave radiation.

(b)  0.167 ms is required by the microwave to travel between two mountains.

Answer:

Explanation:

a. Frequency is the measure of number of times a same thing will be repeated in a given time interval for a given time. And wavelength is the measure of distance between two successive crests or troughs. So wavelength and frequency are inversely proportional to each other. And velocity of light is the proportionality constant.

So frequency of microwave radiation = Speed of light/Wavelength of radiation

Frequency = \frac{3*10^{8} }{3*10^{-2} }

Frequency = 10^{8+2} = 10^{10}=10 GHz

So 10 GHz is the frequency of microwave radiation.

b). As microwave is a part of light waves, so it will be experiencing the speed of light.

As the speed is 3*10^{8} m/s and the distance between the two mountains is given as 50 km, then time can be calculated as

Time = Distance/Velocity

Time = \frac{50*10^{3} m}{3*10^{8} }=16.67*10^{3-8}=16.67*10^{-5}

So time = 0.167 ms.

Thus, 0.167 ms is required by the microwave to travel between two mountains.

6 0
4 years ago
sledge (including load) weighs 5000 N. It is pulled on level snow by a dog team exerting ahorizontal force on it. The coefficient
lara31 [8.8K]

Answer:

2.5 x 10^{5} J

Explanation:

weight = 5,000 N

coefficient of friction = 0.05

distance = 1000 m

how much work is done by the dogs pulling the sledge

work done = force x coefficient of friction x distance

work done = 5000 x 0.05 x 1000 = 2.5 x 10^{5} J

6 0
4 years ago
What pushes against gravity in: a main sequence star, a white dwarf, a neutron star, and a black hole? electron degeneracy, neut
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Answer:

heat pressure, electron degeneracy, neutron degeneracy, and nothing

Explanation:

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White dwarf: It is the end stage of a medium sized star like the Sun. Outer layers of the star are thrown in the form a shell/bubble leaving a small and dense core in the center called as white dwarf. This core consists of carbon and oxygen. Nuclear fusion doesn't occur in the core of white dwarfs. The inward gravity is balanced by the electron degeneracy pressure. Thus these stars will keep on radiating the remaining heat and will turn in to a black dwarf at the end.

Neutron Star: This is the end stage of a supermassive star (1-3 times the mass of the Sun). At the last stage of the life the core collapses. In these stars the inward gravity is so huge that the pressure overcomes the electron degeneracy pressure and crushes together the electron and proton to form neutron. The neutron then stops the collapse and balances the inward gravity.

Black Hole: This is the end stage of a hyper massive stars weighing more than 3 times the mass of the Sun. The inward gravitational force is so huge that even the neutrons are not able to stop the collapse the core. thus the mass of the star collapses into a very small area of immense gravity. There is nothing that can balance this inward gravity.

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3 years ago
A car is moving in uniform circular motion. If the cars speed were to double to keep the car moving with the same radius the acc
Stells [14]

Answer:

<em>The centripetal acceleration would increase by a factor of 4</em>

<em>Correct choice: B.</em>

Explanation:

<u>Circular Motion</u>

The circular motion is described when an object rotates about a fixed point called center. The distance from the object to the center is the radius. There are other magnitudes in the circular motion like the angular speed, tangent speed, and centripetal acceleration. The formulas are:

v_t=w\ r

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\displaystyle a_c=\frac{(2v_t)^2}{r}

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The centripetal acceleration would increase by a factor of 4

Correct choice: B.

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3 years ago
Which of the following is quantitative data? a. Color c. Shape b. Odor d. Volume
Papessa [141]
Hello there! Quantitive data has to do with measurements that can be shown with numbers. Examples of this are things like your height and the length of your arms. With that alone, A and B are eliminated, because those answer choices make no sense. They can't be expressed by numbers and you can't measure colors or odors mathematically. Volume is a way to measure something that CAN be written down by numbers. D is the only answer choice that fits the definition of quantitive data. The answer is D: volume.
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