A ball of mass 2 kg is kept on the hill of height 3 km. Calculate the potential energy possessed by it ?How can I get the potential energy ?

Answers

Answer 1

Answer: We know that -

$P.E=m*g*h$

Where,

$m = mass$

$g = acceleration$ $due$ $to$ $gravity$

$h=height$

First we convert height into meters.

1 km = 1000 meters

3 km = 1000 * 3 meters = 3000 meters

So, putting the values in the above formula, and by taking 'g' = 9.8 m/s², we get-

$P.E.= 2*3000*9.8$

$P.E.= 58800$ $Joules$

$P.E.= 58.8$ $kJ$

Answer 2

Answer: Sairah's work is correct as far as it goes. The potential energy of the ball
relative to the bottom of the hill is 58,800 Joules.

To address the second part of the question:
In order to get ahold of that energy, the ball must be returned to the bottom
of the hill. The most efficient way would be to drop it, so that it wouldn't have to
scrape along the grass on the way down. But that can only work if there's a sheer
cliff on one side of the hill. Otherwise, you just have to roll it down, and accept the
fact that it loses some of its energy to friction on the way.

However the ball gets to the bottom, the energy it has left shows up in the form
of kinetic energy, and 58,800 joules is a lot of kinetic energy. If somehow the ball
could arrive at the bottom with ALL the energy it had at the top, it would be moving
at something like 540 miles per hour !

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Sound is a example of what kind of wave

Answers

Answer: The correct answer is longitudinal wave.

Explanation:

Longitudinal wave: The vibration of the particle is parallel to the direction of the propagation of the wave.

Longitudinal wave consists of the compression and the rarefaction.

Compression is the region where the density of the particles are more. Rarefaction is the region where the density of the particles are less.

The example of the longitudinal wave is Sound wave.

Sound is an example of a longitudinal wave.

The wave function for a traveling wave on a taut string is (in si units) y(x,t) = 0.340 sin 15πt − 4πx + π 4 (a) what are the speed and direction of travel of the wave? g

Answers

Answer:

Explanation:

Given the wave function

y(x,t) = 0.340 sin (15πt − 4πx + π/4)

Generally a wave function is of the form

y(x, t) = A•Sin(wt - kx + θ)

Where

A is amplitude

w is angular frequency

θ is the phase angle

k is the wave number.

Then, comparing this with given wave function

k = 4π, w = 15π and θ = π/4

Speed and direction?

The speed of a wave function can be determined using wave equation

v = fλ

w = 2πf

Then, f = w/2π = 15π/2π = 7.5Hz

Also k = 2π/λ

Then, λ = 2π/k = 2π/4π = 0.5 m

Then,

v = fλ = 7.5 × 0.5

v = 3.75m/s

Direction

Since the time and distance coefficient have opposite sign, for an increasing time interval, the translation will have to increase in the positive direction to nullify the change and maintain the phase. Hence, the wave is traveling in the positive x direction

A rock at the top of a 30 meter cliff has a mass of 25 kg. Calculate the rock’s gravitational potential energy when dropped off the cliff. Assuming that energy is conserved and there is no air friction and gravity is 9.8 m/sec., at the bottom of the cliff the rock’s potential energy is completely converted to kinetic energy. Use the formula for kinetic energy to calculate the rock’s speed at the bottom of the cliff. Show all calculations.

Answers

Potential energy =

   (mass) x (gravity) x (height above the reference level) .

Relative to the bottom of the cliff, the potential energy
at the top of the cliff is

   (25kg) x (9.8 m/s²) x (30 meters)

   = (25 x 9.8 x 30) kg-m²/s²

   = 7,350 joules .

Kinetic energy = (1/2) x (mass) x (speed²)

The rock's kinetic energy at the bottom is
the same as its potential energy at the top.

7,350 joules = (1/2) x (25 kg) x (speed²)

Divide each side
by 12.5kg : 7,350 joules/12.5 kg = speed²

   7,350 kg-m²/s² / 12.5kg = speed²

   (7,350 / 12.5) m²/s² = speed²

      588 m²/s² = speed²
Take the square root
of each side:
   Speed = √(588 m²/s²)

   = 24.248... m/s (rounded)

Lets see:-

We have our formula for potential energy, which we are trying to solve for,

PE = mgh or potential energy = mass * gravity * height

So we know that PE all depends on these.

Height : 30 meters
Mass : 25 kg
Gravity (which is always constant) : 9.8 m/s/s

Now add into formula.

PE = 25*30*9.8
PE = 7350 Joules

Answer: PE = 7350 Joules

At about 55 meters/sec, a falling parachuter (before the parachute opens) no longer accelerates. Air friction opposes acceleration. Although the effect of air friction begins gradually, imagine that the parachuter is free
falling until terminal speed (the constant falling speed) is reached. How long would that take?

Answers

Well, it takes one second to get every 10 meters (if $g=10 m/s^2$ ), so one needs just 5.5 seconds. He would fall 137.5 meters (if my calculations are right) during that time.

Answer:

5.6 seconds

Explanation:

I did the worksheet and got it right

During a phase change what happens to the temperature?

Answers

During a phase change the substance or objects temperature increases or decreases depending on which way they go, Solid to liquid to gas needs added heat which makes it an endothermic reaction. Gas to liquid to solid loses heat energy to slow down its particles this is an exothermic reaction.

The temperature either rises or falls during a state change.
Ex.
Melting from ice to water~ the temperature is rising.

OR

Ex.
From a gas to a liquid~ the temperature is falling.

Compare and contrast the geocentric view of the solar system with the heliocentric view of the solar system

Answers

This is fairly easy. The earlier view of the solar system (geocentric) was all based on how other planets and the sun were constantly revolving the earth and we were completely stationary. The Heliocentric view has been proved to be accurate, and it is that the sun is stationary and the planets are revolving it. The similarities are that in that time, it was a continued belief that the planets were the Roman Gods, i.e. Jupiter, Neptune. Another thing is that they were correct in the Geocentric theory with the thought that the planets revolved around something.

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