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3 years ago

A body having uniform velocity has zero acceleration? give reason

Physics

2 answers:

Gala2k [10]3 years ago

8 0

Explanation:

A body having uniform velocity has zero acceleration because its initial and final velocity are same

i.e,v=u

by the formula of acceleration,we have

v-u/t

=v-v/t

=0/t

Sonja [21]3 years ago

5 0

Answer:

A body having uniform velocity has zero acceleration because

there is not change in velocity.

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A person throws a stone from the corner edge of a building. The stone's initial velocity is 28.0 m/s directed at 43.0° above the

Naya [18.7K]

The stone's acceleration, velocity, and position vectors at time $t$ are

$\mathbf a(t)=-g\,\mathbf j$

$\mathbf v(t)=v_{i,x}\,\mathbf i+\left(v_{i,y}-gt\right)\,\mathbf j$

$\mathbf r(t)=v_{i,x}t\,\mathbf i+\left(y_i+v_{i,y}t-\dfrac g2t^2\right)\,\mathbf j$

where

$g=9.80\dfrac{\rm m}{\mathrm s^2}$

$v_{i,x}=\left(28.0\dfrac{\rm m}{\rm s}\right)\cos43.0^\circ\approx20.478\dfrac{\rm m}{\rm s}$

$v_{i,y}=\left(28.0\dfrac{\rm m}{\rm s}\right)\sin43.0^\circ\approx19.096\dfrac{\rm m}{\rm s}$

and $y_i$ is the height of the building and initial height of the rock.

(a) After 6.1 s, the stone has a height of 5 m. Set the vertical component $(\mathbf j)$ of the position vector to 5 m and solve for $y_i$ :

$5\,\mathrm m=y_i+\left(19.096\dfrac{\rm m}{\rm s}\right)(6.1\,\mathrm s)-\dfrac12\left(9.80\dfrac{\rm m}{\mathrm s^2}\right)(6.1\,\mathrm s)^2$

$\implies\boxed{y_i\approx70.8\,\mathrm m}$

(b) Evaluate the horizontal component $(\mathbf i)$ of the position vector when $t=6.1\,\mathrm s$ :

$\left(20.478\dfrac{\rm m}{\rm s}\right)(6.1\,\mathrm s)\approx\boxed{124.92\,\mathrm m}$

(c) The rock's velocity vector has a constant horizontal component, so that

$v_{f,x}=v_{i,x}\approx20.478\dfrac{\rm m}{\rm s}$

where $v_{f,x}$

For the vertical component, recall the formula,

${v_{f,y}}^2-{v_{i,y}}^2=2a\Delta y$

where $v_{i,y}$ and $v_{f,y}$ are the initial and final velocities, $a$ is the acceleration, and $\Delta y$ is the change in height.

When the rock hits the ground, it will have height $y_f=0$ . It's thrown from a height of $y_i$ , so $\Delta y=-y_i$ . The rock is effectively in freefall, so $a=-g$ . Solve for $v_{f,y}$ :

${v_{f,y}}^2-\left(19.096\dfrac{\rm m}{\rm s}\right)^2=2(-g)(-124.92\,\mathrm m)$

$\implies v_{f,y}\approx-53.039\dfrac{\rm m}{\rm s}$

(where we took the negative square root because we know that $v_{f,y}$ points in the downward direction)

So at the moment the rock hits the ground, its velocity vector is

$\mathbf v_f=\left(20.478\dfrac{\rm m}{\rm s}\right)\,\mathbf i+\left(-53.039\dfrac{\rm m}{\rm s}\right)\,\mathbf j$

which has a magnitude of

$\|\mathbf v_f\|=\sqrt{\left(20.478\dfrac{\rm m}{\rm s}\right)^2+\left(-53.039\dfrac{\rm m}{\rm s}\right)^2}\approx\boxed{56.855\dfrac{\rm m}{\rm s}}$

(d) The acceleration vector stays constant throughout, so

$\mathbf a(t)=\boxed{-g\,\mathbf j}$

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3 years ago

The Whirlpool galaxy is about 30 million light-years away. If you were in a spaceship that could travel at half of the speed of

Nataly_w [17]

Answer:

51.96 years

2) 30 million of years

Explanation:

First we must know the travel time of the ship seen from the earth. The spaceship travels at half the speed of light, this means that the amount of time the spacecraft must spend to travel the same distance is double compared to the light, that is 60 years.

Now due to the speed of the ship, we must take into account relativistic effects, such as time dilation, this is given by:

$t'=\frac{t}{\sqrt{1-\frac{v^2}{c^2}}}$

Where t is the time measured in the ship, t' is the time measured in the earth, inertially moving with velocity v.

Rewriting for t:

$t=t'\sqrt{1-\frac{v^2}{c^2}}\\t=60\sqrt{1-\frac{(0.5c)^2}{c^2}}\\t=60\sqrt{1-0.5^2}\\t=51.96 years$

This is the amount of time it would take you reach the Whirlpool galaxy in the spaceship.

2) a light year is a measure of distance, which indicates the kilometers that light travels in a year. Thus, the light emitted by Whirlpool galaxy takes 30 million of years reaches our planet.

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3 years ago

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Answer:about 200,000 years ago that humans existed on earth.

Explanation:Geologic time refers to the planet's changing geology. The earliest fossils of modern humans are from the middle Paleolithic about 200,000 years ago such as the omo remains from Ethiopia and the fossil of herto classified equally as homosapiens equally from Ethiopia.

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3 years ago

The voltage in a circuit can be determined from the ____, total resistance, and capacitance

Dmitrij [34]

I think the answer is D, but I’m not at all sure :l

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4 years ago

this event is the result of a sudden vertical offset in the ocean floor and is most often the result of plate movement on the oc

MissTica

Answer: Tsunami.

Explanation :

Tsunami is the result of a sudden vertical offset in the ocean floor and is most often the result of plate movement on the ocean floor.

Tsunami is caused due to the displacement of a large volume of water like in an ocean. It consists of a series of waves. It destroys coastlines and coastal settlements. It is also known as a tidal wave.

So, the correct option is (b) Tsunami.

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3 years ago

A body having uniform velocity has zero acceleration? give reason​

A body having uniform velocity has zero acceleration? give reason