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4 years ago

15

a person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of 18 m/s. The cliff is 52 m above the

water's surface. With what speed did it strike the water?

2 answers:

Evgesh-ka [11]4 years ago

8 0

Answer:

Speed with which it strike the water = 36.66 m/s

Explanation:

Horizontal component of velocity = 18 m/s

We need to find vertical component of velocity.

Considering vertical motion of stone

Initial velocity, u = 0 m/s

Acceleration , a = 9.81 m/s²

Displacement, s = 52 m

We have equation of motion v² = u² + 2as

Substituting

v² = u² + 2as

v² = 0² + 2 x 9.81 x 52

v = 31.94 m/s

Vertical component of velocity = 31.94 m/s

$\texttt{Total velocity = }\\\\\sqrt{\texttt{Horizontal component of velocity}^2+\texttt{Vertical component of velocity}^2}\\\\\texttt{Total velocity = }\sqrt{18^2+31.94^2}=36.66m/s$

Speed with which it strike the water = 36.66 m/s

Alexxx [7]4 years ago

7 0

You already have the speed, now you need the time.
I will use the formula for speed which is S=D/T.
S=Speed D=Distance T=Time.
So here we have, 18m/s = 52m/T
we do 18 divided by 52 which would be .3461.
.3461 seconds is how long it took the stone to reach the water.

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A wire carries a current of 0.66 A. This wire makes an angle of 58° with respect to a magnetic field of magnitude 5.50 10-5 T. T

Oliga [24]

Answer:

The length of the wire is "1.93 m".

Explanation:

Given:

Current,

I = 0.66 A

Angle,

$\Theta$ = 58°

Magnetic field of magnitude,

F = $5.5\times 10^{-5}$ N

The length of the wire will be:

⇒ $F = B\times I\times L\times Sin \Theta$

or,

⇒ $L = \frac{F}{B\times I\times Sin \theta}$

By putting the values, we get

$=\frac{5.5\times 10^{-5}}{0.66\times 5.1\times 10^{-5}\times Sin \ 58^{\circ}}$

$=\frac{5.5}{2.828}$

$=1.93 \ m$

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3 years ago

An object moves in a straight path. Its position x as a function of time t is presented by the equation x(t) = at – bt2+c, where

ankoles [38]

Answer:

The answer is below

Explanation:

Given that:

x(t) = at – bt2+c

a) x(t) = at – bt2+c

Substituting a = 1.4 m/s, b = 0.06 m/s2 and c =50 m gives:

x(t) = 1.4t - 0.06t² + 50

At t = 5, x(5) = 1.4(5) - 0.06(5)² + 50 = 55.5 m

At t = 0, x(0) = 1.4(0) - 0.06(0)² + 50 = 50 m

The average velocity (v) is given as:

$v=\frac{x(5)-x(0)}{5-0}\\ \\v=\frac{55.5-50}{5-0}=1.1\\ \\v=1.1\ m/s$

b) x(t) = 1.4t - 0.06t² + 50

At t = 10, x(10) = 1.4(10) - 0.06(10)² + 50 = 58 m

At t = 0, x(0) = 1.4(0) - 0.06(0)² + 50 = 50 m

The average velocity (v) is given as:

$v=\frac{x(10)-x(0)}{10-0}\\ \\v=\frac{58-50}{10-0}=0.8\\ \\v=0.8\ m/s$

c) x(t) = 1.4t - 0.06t² + 50

At t = 15, x(5) = 1.4(15) - 0.06(15)² + 50 = 57.5 m

At t = 10, x(10) = 1.4(10) - 0.06(10)² + 50 = 58 m

The average velocity (v) is given as:

$v=\frac{x(15)-x(10)}{15-10}\\ \\v=\frac{57.5-58}{15-10}=0.1\\ \\v=0.1\ m/s$

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3 years ago

An Olympic diver springs off of a high dive that is 3 m above the surface of the water. When she lands in the water she is trave

klemol [59]

Answer: $u=4.51 m/s\ at\ angle\ of\ \theta =59.34^{\circ}$

Explanation:

Given

height of building h=3 m

Landing velocity of diver $v=8.90 m/s$ at an angle of $75^{\circ}$

Let u be the initial velocity of diver at an angle of \theta with horizontal

Since there is no acceleration in horizontal direction therefore horizontal component of velocity will remain same

$u\cos \theta =8.9\cos (75)$ ---- -----1

Considering Vertical motion

$v^2-u^2=2as$

here $v=8.9\sin (75)$

$u=u\sin \theta$

$s=3 m$

$a=9.8 m/s^2$

$(8.9\sin (75))^2-(u\sin \theta )^2=2\times 9.8\times 3$

$u\sin \theta =\sqrt{(8.9\sin 75)^2-(2\cdot 9.8\cdot 3)}$

$u\sin \theta =3.886$ ----------------2

Divide 2 and 1 we get

$\tan \theta =\frac{3.886}{8.9\cos (75)}$

$\tan \theta =1.687$

$\theta =59.34^{\circ}$

Thus $u\cos (59.34)=8.9\cos (75)$

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kogti [31]

Answer:

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Explanation:

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If the back of his house=x ft

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Note that the farmer does not fence the side on the back of the house.

Area of the garden = 400 square feet

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x+40=0 or x-10=0

x=-40 or x=10

Since length cannot be negative, x=10 ft

The Length of the Fencing the farmer will buy will be the perimeter of the three sides.

Perimeter of the three sides = x+(x+30)+(x+30)

=3x+60

=3(10)+60=90 ft

The farmer needs to buy a fencing of length 90 feet.

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diamong [38]

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4 years ago

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