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3 years ago

What is the velocity of an object that has been in free fall for 1.5s?

Physics

1 answer:

Crank3 years ago

8 0

Answer:

D. 15 m/s downward

Explanation:

v = at + v₀

v = (-9.8 m/s²) (1.5 s) + (0 m/s)

v = -14.7 m/s

Rounded to two significant figures, the answer is D, 15 m/s downward.

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A swimmer bounces straight up from a diving board and falls feet first into a pool. She starts with a velocity of 4.00 m/s, and

Svetlanka [38]

Answer:

a = 1.152s

b = 0.817 m

c = 7.29m/s

Explanation: let the following

From the first equation of linear motion

V = u+at..........1

parameters be represented as :

t = Time taken

v = Final velocity

a = Acceleration due to gravity = 9.8m/s²

u = Initial velocity = 4 m/s

s = Displacement

V = 0

Substitute the values into equation 1

0 = 4-9.8(t)

-4 = -9.8t

t = 4/9.8

t = 0.408s

From : s = ut+1/2at^2.........2

S = 4×0.408+0.5(-9.8)×0.408^2

S= 1.632-4.9(0.166)

S = 1.632-0.815

S = 0.817m

Her highest height above the board is 0.817 m

Total height she would fall is 0.817+1.90 = 2.717 m

From equation 2

s = ut+1/2at^2

2.717 m = 0t+0.5(9.8)t^2

2.717 m = 0+4.9t^2

2.717 m = 4.9t^2

2.717/4.9 = t^2

0.554 =t^2

t =√0.554

t = 0.744s

Hence, her feet were in the air for 0.744+0.408seconds

= 1.152s

Also recall from equation 1

V= u+at

V = 0+9.8(0.744)

V = 7.29m/s

Hence, the velocity when she hits the water is 7.29m/s

Finally,

a = 1.152s

b = 0.817 m

c = 7.29m/s

4 0

3 years ago

The intensity level is 65 db at a distance 5.00 m from a barking dog. What would be a reasonable estimate for the intensity leve

BARSIC [14]

Answer:

68 db

Explanation:

Since now instead of one two dogs are barking simultaneously close to each other, therefore we take n =2.

Ignoring interference effects, the barking of two dogs result in a higher level of intensity which is given by,

β(db)=10×㏒(2)

=3 db

So, a reasonable estimate for the raised Intensity Level is: 65db+3db = 68db

7 0

3 years ago

Please who can give me the definition of density in terms of Archimedes principle.

VladimirAG [237]

$\large\bold{\underline{\underline{Answer:-}}}$

The weight of the fluid displaced is equal to the buoyant force on a submerged object. The mass divided by the volume thus determined gives a measure of the average density of the object.

8 0

2 years ago

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A starship blasts past the earth at 2.0*10^8 m/s .Just after passing the earth, the starship fires a laser beam out its back of

Vilka [71]

Answer:

at the speed of light ( $c=3.0\cdot 10^8 m/s$ )

Explanation:

The second postulate of the theory of the special relativity from Einstein states that:

"The speed of light in free space has the same value c in all inertial frames of reference, where $c=3.0\cdot 10^8 m/s$ "

This means that it doesn't matter if the observer is moving or not relative to the source of ligth: he will always observe light moving at the same speed, c.

In this problem, we have a starship emitting a laser beam (which is an electromagnetic wave, so it travels at the speed of light). The startship is moving relative to the Earth with a speed of 2.0*10^8 m/s: however, this is irrelevant for the exercise, because according to the postulate we mentioned above, an observer on Earth will observe the laser beam approaching Earth with a speed of $c=3.0\cdot 10^8 m/s$ .

7 0

3 years ago

Define rectilinear propagation of light.??

Tju [1.3M]

Answer:

it relates to the light propensity to travel over one straight line without having any interference in its trajectory

Explanation:

5 0

3 years ago

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