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3 years ago

an object moving with a speed of 5 m/s has a kinetic energy of 100 J. what is the mass of the object?

Physics

1 answer:

elixir [45]3 years ago

5 0

Answer:40kg

Explanation:

Velocity(v)=5m/s

Kinetic energy(ke)=100j

mass=?

Mass=(2xke) ➗ v^2

Mass=(2x500) ➗ 5^2

Mass=1000 ➗ 5x5

Mass=1000 ➗ 25

Mass=40kg

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A spotlight on the ground shines on a wall 12 m away. If a man 2 m tall walks from the spotlight toward the building at a speed

mafiozo [28]

Answer:

0.6375 m/s

Explanation:

Let x be the distance of the man from the building

from the figure attached

initially the value of x=12

Given:

$\frac{dx}{dt}=-1.7m/s$

where the negative sign depicts that the distance of the man from the building is decreasing.

Now, Let The length of the shadow be = y

we have to calculate $\frac{dy}{dt}$ when x=4

from the similar triangles

we have,

$\frac{2}{12-x}=\frac{y}{12}$

$y=\frac{24}{12-x}$

Differentiating with respect to time 't' we get

$\frac{dy}{dt}=-\frac{24}{12-x}^2\frac{-dx}{dt}$

$\frac{dy}{dt}=\frac{24}{12-x}^2\frac{dx}{dt}$

Now for x = 4, and $\frac{dx}{dt}=-1.7m/s$ we have,

$\frac{dy}{dt}=\frac{24}{12-4}^2\times (-1.7)$

$\frac{dy}{dt}=-0.6375m/s$

<u>here, the negative sign depicts the decrease in length and in the question it is asked the decreasing rate thus, the answer is </u><u>0.6375m/s</u>

4 0

3 years ago

Which statement about homeostasis is true?

Debora [2.8K]

Answer: Homeostasis helps to maintain body equilibrium.

Explanation:

Homeostasis is defined as the maintenance of a fairly constant internal environment in an organism. Body fluids such as blood, lymph, and tissue fluids make up the internal environment of the body, hence by the action of the nervous and endocrine system, there levels are maintained at a body equilibrium, by the help of brain, which has overall control of homeostasis while other parts such as kidney, liver, skin, hormones are also involved.

3 0

2 years ago

Tom kicks a soccer ball on a flat, level field giving it an initial speed of 20 m/s at an angle of 35 degrees above the horizont

SVEN [57.7K]

Answer:

(a) 2.34 s

(b) 6.71 m

(d) 20 m/s

Explanation:

u = 20 m/s, theta = 35 degree

(a) The formula for the time of flight is given by

$T = \frac{2 u Sin\theta }{g}$

$T = \frac{2 \times 20 \times Sin35 }{9.8}$

T = 2.34 second

(b) The formula for the maximum height is given by

$H = \frac{u^{2} \times Sin^{2}\theta }{2g}$

$H = \frac{20^{2} \times Sin^{2}35 }{2 \times 9.8}$

H = 6.71 m

$R = \frac{u^{2} \times Sin 2\theta }{g}$

$R = \frac{20^{2} \times Sin 2 \times 35}{9.8}$

R = 38.35 m

(d) It hits with the same speed at the initial speed.

8 0

3 years ago

How can we balance the use of fossil fuels with other forms of energy?

KiRa [710]

We can use renewable sources

4 0

3 years ago

What will change the velocity of a periodic wave?

Georgia [21]

If it's a mechanical wave, then its speed depends on the physical characteristics of the medium.

If it's an electromagnetic wave, then its speed depends on the
electrical characteristics of the medium.

Either way, the properties of the medium determine the wave speed.
You want to change the speed ? You have to change the properties
of the medium.

7 0

2 years ago