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NeTakaya
3 years ago
11

A person standing at the edge of a seaside cliff kicks a stone horizontally over the edge with a speed of 18 m/s. The cliff is 5

2 meters above the water's surface. How long does it take for the stone to fall to the water?
Physics
1 answer:
Fed [463]3 years ago
7 0

Answer:

it would take 3.26 seg for the stone to fall to the water

Explanation:

If we ignore air friction then:

h=h₀ + v₀*t -1/2*g*t²

where

h= coordinates of the stone in the y axis ( height of the stone relative to the surface of the water )

h₀ = initial coordinates of the stone ( height of the cliff relative to the surface of the water = 52 m )

v₀ = initial <u>vertical </u>velocity = 0 ( since the ball is kicked horizontally , has only initial horizontal velocity , and has 0 vertical velocity )

t = time to reach a height h

g = gravity = 9.8 m/s²

since v₀ =0

h= h₀ - 1/2*g*t²

h₀ - h =  1/2*g*t²

t= √[2(h₀ - h)/g]

when the stone hits the ground h=0 ( height=0) , then replacing values

t=√[2(h₀ - h)/g]=√[2(52 m- 0 m )/(9.8m/s²)] = 3.26 seg

t= 3.26 seg

it would take 3.26 seg for the stone to fall to the water

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what is the value of the constant for a second order reaction if the reactant concentration drops from .657 M to ,0981 M in 17 s
yaroslaw [1]

Answer : The value of the constant for a second order reaction is, 0.51M^{-1}s^{-1}

Explanation :

The expression used for second order kinetics is:

kt=\frac{1}{[A_t]}-\frac{1}{[A_o]}

where,

k = rate constant = ?

t = time = 17s

[A_t] = final concentration = 0.0981 M

[A_o] = initial concentration = 0.657 M

Now put all the given values in the above expression, we get:

k\times 17s=\frac{1}{0.0981M}-\frac{1}{0.657M}

k=0.51M^{-1}s^{-1}

Therefore, the value of the constant for a second order reaction is, 0.51M^{-1}s^{-1}

6 0
3 years ago
A vocalist with a bass voice can sing as low as 92 Hz.
Inessa05 [86]

Answer:

  • 3.26 x 10 to the power of 6

Explanation:

c = lambda × frequency

5 0
3 years ago
In a crash test, a truck with mass 2100 kg traveling at 22 m/s smashes head-on into a concrete wall without rebounding. The fron
slega [8]

Answer:

a)   v_average = 11 m / s, b)  t = 0.0627 s

, c)    F = 7.37 10⁵ N

, d)   F / W = 35.8

Explanation:

a) truck speed can be found with kinematics

         v² = v₀² - 2 a x

The fine speed zeroes them

           a = v₀² / 2x

           a = 22²/2 0.69

           a = 350.72 m / s²

The average speed is

           v_average = (v + v₀) / 2

           v_average = (22 + 0) / 2

           v_average = 11 m / s

b) The average time

          v = v₀ - a t

          t = v₀ / a

          t = 22 / 350.72

          t = 0.0627 s

c) The force can be found with Newton's second law

             F = m a

             F = 2100 350.72

             F = 7.37 10⁵ N

.d) the ratio of this force to weight

             F / W = 7.37 10⁵ / (2100 9.8)

             F / W = 35.8

.e) Several approaches will be made:

- the resistance of air and tires is neglected

- It is despised that the force is not constant in time

- Depreciation of materials deformation during the crash

5 0
2 years ago
If the wagon travels 18.75 m, what is the work done on the wagon
Schach [20]

If the wagon travels 18.75 m, then the work done on the wagon is

(18.75 m) x (the steady force applied to the wagon all the way, in Newtons) .

The unit is Joules .


4 0
3 years ago
A refrigerator is 1.8m tall, lm wide,and 0.8m deep.The center of mass is lm from the bottom, 0.5m from the side, and 0.6m from t
VikaD [51]

Answer:

  F = 520 N

Explanation:

For this exercise the rotational equilibrium equation should be used

          Σ τ = 0

Let's set a reference system with the origin at the back of the refrigerator and the counterclockwise rotation as positive. On the x-axis it is horizontal directed outward, eg the horizontal y-axis directed to the side and the z-axis vertical

Torque is

             τ = F x r

the bold indicate vectors, we analyze each force

the applied force is horizontal along the -x axis, the arm (perpendicular distance) is directed in the z axis,

The weight of the body is the vertical direction of the z-axis, so the arm is on the x-axis

                 -F z + W x = 0

                 F z = W x

                 F =  \frac{x}{z}  W

             

The exercise indicates the point of application of the force z = 1.5 m and the weight is placed in the center of mass of the body x = 0.6 m, we are assuming that the force is applied in the wide center of the refrigerator

let's calculate

                 F = 1300 0.6 / 1.5

                 F = 520 N

5 0
3 years ago
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