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creativ13 [48]
3 years ago
11

1. A 1,000-kg car has 50,000 joules of kinetic energy. What is its speed?

Physics
2 answers:
bulgar [2K]3 years ago
4 0
Use KE= 1/2mv^2
So... 
50,000=(.5)(1,000)v^2
50,000=500 x v^2
Divide 500 on both sides 
100 = v^2 
Square root both sides to get rid of v^2 
Therefore v = 10 m/s
Crank3 years ago
3 0

½mv²= KE  

½(1000)?²= 50000

500*?²= 50000

/500            /500

? ²=100

Square root  

?= 10

10 m/s is you answer

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Cars are the mechanical device which convert chemical energy of fuel into mechanical energy, the engine used in the automobiles car are very inefficient, they can only convert 30-40% of chemical energy of fuel into mechanical energy, since thermodynamics is the branch of science that deals with the conversion of energy, thus due to poor conversion rate of chemical energy into mechanical energy, cars are known as inefficient machine.

6 0
3 years ago
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a stone with a mass of 2.40 kg is moving with velocity (6.60î − 2.40ĵ) m/s. find the net work (in j) on the stone if its velocit
ch4aika [34]

By the work energy theorem, the total work done on the stone is given by its change in kinetic energy,

W = \Delta K = \dfrac m2 ({v_2}^2 - {v_1}^2)

We have

\vec v_1 = (6.60\,\vec\imath - 2.40\,\vec\jmath)\dfrac{\rm m}{\rm s} \implies {v_1}^2 = \|\vec v_1\|^2 = 49.32 \dfrac{\rm m^2}{\rm s^2}

\vec v_2 = (8.00\,\vec\imath + 4.00\,\vec\jmath) \dfrac{\rm m}{\rm s} \implies {v_2}^2 = \|\vec v_2\|^2 = 80.0\dfrac{\mathrm m^2}{\mathrm s^2}

Then the total work is

W = \dfrac{2.40\,\rm kg}2 \left(80.0\dfrac{\rm m^2}{\rm s^2} - 49.32\dfrac{\rm m^2}{\rm s^2}\right)  \approx \boxed{36.8\,\rm J}

5 0
2 years ago
A ball is dropped off the roof of a tall building. If the ball reaches the ground in 8 seconds, how tall is the building, in met
Ghella [55]

Let <em>b</em> be the height of the building, and <em>y</em> the height of the ball at time <em>t</em>, given by

<em>y</em> = <em>b</em> - 1/2 <em>gt</em>²

where <em>g</em> = 9.8 m/s² is the magnitude of the acceleration due to gravity.

It takes the ball 8 s to reach the ground, at which point <em>y</em> = 0, so that

0 = <em>b</em> - 1/2 (9.8 m/s²) (8 s)²

<em>b</em> = 1/2 (9.8 m/s²) (8 s)²

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3 years ago
To persuade my audience that the use of mobile communication devices by drivers—even when they are hands-free—is contributing to
pickupchik [31]

Answer:

specific purpose statement      

Explanation:

It is a specific purpose statement made for a persuasive speech on the question of fact.

A specific purpose statement helps to build on the general purpose (that is to inform) and to make it more specific to the audience. So if the first speech is an informative speech, our general purpose is to inform our audience about a very specific realm of knowledge.

A specific purpose statement is given to audience to persuade on specific information.

8 0
3 years ago
How much work must be done by frictional forces in slowing a 1000-kg car from 26.1 m/s to rest? a.3.41 x 10^5 J b.2.73 x 10^5 J
algol13

Answer:

Work done by the frictional force is 3.41\times 10^5\ J

Explanation:

It is given that,

Mass of the car, m = 1000 kg

Initial velocity of car, u = 26.1 m/s

Finally, it comes to rest, v = 0

We have to find the work done by the frictional forces. Work done is equal to the change in kinetic energy as per work - energy theorem i.e.

W=k_f-k_i

W=\dfrac{1}{2}m(v^2-u^2)

W=\dfrac{1}{2}\times 1000\ kg(0^2-(26.1\ m/s)^2)

W = −340605 J

or

W=3.41\times 10^5\ J

Hence, the correct option is (a).

6 0
3 years ago
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