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3 years ago

In a race, you run 3000 meters east in 21 minutes. What is your velocity in km/min?

1 answer:

6 0

velocity = distance / time v= d/t firstly you change 3000 m into km distance D = 3000/1000 = 3 km secondly time t = 21 min using velocity formula v = d/t = 3 km/21min =0.142km/min

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Physics help please

zhuklara [117]

Answer: 37.981 m/s

Explanation:

This situation is related to projectile motion or parabolic motion, in which the travel of the ball has two components: x-component and y-component. Being their main equations as follows:

x-component:

$x=V_{o}cos\theta t$ (1)

Where:

$x=52 m$ is the point where the ball strikes ground horizontally

$V_{o}$ is the ball's initial speed

$\theta=0$ because we are told the ball is thrown horizontally

$t$ is the time since the ball is thrown until it hits the ground

y-component:

$y=y_{o}+V_{o}sin\theta t+\frac{gt^{2}}{2}$ (2)

Where:

$y_{o}=120m$ is the initial height of the ball

$y=0$ is the final height of the ball (when it finally hits the ground)

$g=-9.8m/s^{2}$ is the acceleration due gravity

Knowing this, let's start by finding $t$ from (2):

$0=y_{o}+V_{o}sin(0\°) t+\frac{gt^{2}}{2}$ (3)

$0=y_{o}+\frac{gt^{2}}{2}$

$t=\sqrt{\frac{-2 y_{o}}{g}}$ (4)

$t=\sqrt{\frac{-2 (120 m)}{-9.8m/s^{2}}}$ (5)

$t=4.948 s$ (6)

Then, we have to substitute (6) in (1):

$x=V_{o}cos(0\°) t$ (7)

And find $V_{o}$ :

$V_{o}=\frac{x}{t}$ (8)

$V_{o}=\frac{52 m}{4.948 s}$ (9)

$V_{o}=10.509 m/s$ (10)

On the other hand, since we are dealing with constant acceleration (due gravity) we can use the following equation to find the value of the ball's final velocity $V$ :

$V=V_{o} + gt$ (11)

$V=10.509 m/s + (-9.8 m/s^{2})(4.948 s)$ (12)

$V=-37.981 m/s$ (13) This is the ball's final velocity, and the negative sign indicates its direction is downwards.

However, we were asked to find the ball's final speed, which is the module of the ball's final vleocity vector. This module is always positive, hence the speed of the ball just before it strikes the ground is 37.981 m/s (positive).

5 0

3 years ago

The mass of Jupiter is 1.9 × 1027 and that of the sun is 1.99 × 1030. The

n200080 [17]

Answer:

F = 4.147 × 10^23

v = 1.31 × 10^4

Explanation:

Given the following :

mass of Jupiter (m1) = 1.9 × 10^27

Mass of sun (m2) = 1.99 × 10^30

Distance between sun and jupiter (r) = 7.8 × 10^11m

Gravitational force (F) :

(Gm1m2) / r^2

Where ; G = 6.673×10^-11 ( Gravitational constant)

F = [(6.673×10^-11) × (1.9 × 10^27) × (1.99 × 10^30)] / (7.8 × 10^11)^2

F = [25.231 × 10^(-11+27+30)] / (60.84 × 10^22)

F = (25.231 × 10^46) / (60.84 × 10^22)

F = 3.235 × 10^(46 - 22)

F = 0.4147 × 10^24

F = 4.147 × 10^23

Speed of Jupiter (v) :

v = √(Fr) / m1

v = √[(4.147 × 10^23) × (7.8 × 10^11) / (1.9 × 10^27)

v = √32.3466 × 10^(23+11) / 1.9 × 10^27

v = √32.3466× 10^34 / 1.9 × 10^27

v = √17. 023 × 10^34-27

v = √17.023 × 10^7

v = 13047.221

v = 1.31 × 10^4

4 0

3 years ago

1. Define dark matter and dark energy, and clearly distinguish between them. What types of observations have led scientists to p

Vlada [557]

Explanation:

Dark Energy is a property of the entire universe. And the universe is roughly made up of 68% of this dark energy whereas dark matter makes up 27% of the universe matter.

The influence of the dark matter shows in the individual galaxies whereas dark energy acts only on the entire universe. dark matter is responsible for the gravity effect on the plants and the heavenly bodies which produces gravity force. But the dark energy is known as the anti gravity force as it is responsible for the expansion of the universe. Dark matter attracts and produces an attractive force while dark energy repels and produces a repulsive force.

Scientist believe that they exists to account for the very fact that gravity holds all the heavenly bodies and the galaxies together. They are even responsible for the fluctuation in Cosmic Microwave background. Researchers and scientist firmly believe that all the visible matter that exists may not have enough gravitational pull to hold everything together in the galaxies. And also the expanding universe strongly proves that dark energy exists in the universe.

7 0

3 years ago

A trombone plays a C3 note. If the speed of sound in air is 343 m/s and the wavelength of this note is

Umnica [9.8K]

The frequency of note C3 is 131 $s^{-1}$ .

Explanation:

Frequency is the measure of repetition of same thing a certain number of times. So frequency is inversely proportional to the wavelength. As wavelength is distance between two successive crests or troughs in a sound wave.

And frequency is the completion of number of cycles in a given time in sound waves. The frequency and wavelength are inversely proportional to each other with velocity of sound being the proportionality constant.

Thus, here the speed of sound is given as 343 m/s, the wavelength of the note is also given as 2.62 m, then frequency will be as follows:

$Frequency=\frac{speed of sound}{Wavelength of note}$

Thus,

$Frequency = \frac{343 m/s}{2.62 m} = 131 s^{-1}$

So the frequency of note C3 is 131 $s^{-1}$ .

3 0

3 years ago

Which of the following mixture can be separate using decantation method?

vivado [14]

Answer:

Hi sorry for answering here but you didnt put the options there

Explanation:

I'll still try to answer though so maybe the mixture from one of the questions might be something like oil and water which don't mix and can be separated by decantation so something similar would work. Hope this helps

3 0

3 years ago