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ella [17]
3 years ago
6

A stone dropped from the top of a 80m high building strikes the ground at 40 m/s after falling for 4 seconds. The stone's potent

ial energy with respect to the ground is equal to its kinetic energy … (use g = 10 m/s 2)
A) at the moment of impact.
B) 2 seconds after the stone is released.
C) after the stone has fallen 40 m.
D) when the stone is moving at 20 m/s.

At the moment of impact both Kinetic Energy and Potential Energy should be 0, right? So it can't be A), right? Or is this wrong? Is it indeed A)? Please show work and explain it well.
Physics
1 answer:
Sergeu [11.5K]3 years ago
3 0

Answer: c. 40m

Explanation:

See picture

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KengaRu [80]
<span>The correct option is D) both A and B. In fact, the strength of an electric field produced by a single point charge is given by
</span>E=k  \frac{Q}{r^2}<span>
where Q is the charge that generates the field, k is the Coulomb's constante and r is the distance from the charge source of the field.

From the equation, we see that the strength of the field depends on A) the amount of charge that produced the field (Q) and B) the distance from the charge (r), so the correct option is D.</span>
5 0
3 years ago
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Calculate the (absolute) pressure at the bottom of a neighborhood swimming pool 30.0 m by 8.0 m whose uniform depth is 2.0 m. Th
Alika [10]

Answer:

Total pressure= 120945[Pa]

Force exerted = 29026800 [N] or 29.02*10^6 [N]

Explanation:

We know that the total pressure is the result of the sum of the atmospheric pressure plus the manometric pressure. The equation is:

Ptotal=Patm + Pman

In this problem we know the atmospheric pressure 101.325x10^3 [Pa], therefore we need to find the manometric pressure.

The manometric pressure in the bottom of the swimming pool depends only on the water column of water generated (depth of the swimming pool)

Pman = density*g*h

where:

density = density of the water 1000 [kg/m^3]

g= gravity [m/s^2]

h= column of water (meters)

replacing the values:

Pman= 1000 *9.81* 2 = 19620 [Pa]\\\\

The total pressure will be:

Ptotal= 101325+19620 = 120945 [Pa]\\\\

The force exerte on the bottom is defined by the following expression:

Pressure=Force/area\\\\Force= Pressure*Area\\\\Area = 30m*8m= 240 m^2Force= 120945*240\\Force= 29026800N or 2958 Ton

4 0
4 years ago
Which would ultimately cause the armature in an electric motor to spin?
malfutka [58]
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4 years ago
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Two hockey pucks, labeled A and B, are initially at rest on a smooth ice surface and are separated by a distance of 18.0 m . Sim
Nonamiya [84]

Answer:

The distance covered by puck A before collision is  z = 8.56 \ m

Explanation:

From the question we are told that

   The label on the two hockey pucks is  A and  B

    The distance between the  two hockey pucks is D   18.0 m

     The speed of puck A is  v_A =  3.90 \ m/s

        The speed of puck B is  v_B  =  4.30 \ m/s

The distance covered by puck A is mathematically represented as

     z =  v_A * t

  =>  t  =  \frac{z}{v_A}

 The distance covered by puck B  is  mathematically represented as

      18 - z =  v_B  * t

=>   t  = \frac{18 - z}{v_B}

Since the time take before collision is the same

        \frac{18 - z}{V_B}  =  \frac{z}{v_A}

substituting values

          \frac{18 -z }{4.3}  = \frac{z}{3.90}

=>      70.2 - 3.90 z   = 4.3 z

=>       z = 8.56 \ m

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When a electric current is passed threw water during electrolysis, 2 gases are formed. 1 gas has a boiling point of -183°C and t
Keith_Richards [23]

Answer:

Sorrry so very hard

Ok hahaha

8 0
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