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NemiM [27]
2 years ago
4

A piece of paper with mass 0.002 kg falls from a height of 8 m. under realistic conditions, it experiences air resistance. based

on what you know about friction, what can you say about the kinetic energy of the paper as it reaches the ground? acceleration due to gravity is g = 9.8 m/s2.
Physics
2 answers:
love history [14]2 years ago
7 0

Answer:

KE < 0.16 J is the answer

inna [77]2 years ago
3 0
The potential energy of the paper before falling:
P.E = mgh
= 0.002 x 9.8 x 8
= 0.157 Joules

The kinetic energy of the paper right before hitting the ground will be less than 0.157 Joules because some of its potential energy will be lost as heat energy due to air resistance.
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A 250 GeV beam of protons is fired over a distance of 1 km. If the initial size of the wave packet is 1 mm, find its final size
Margarita [4]

Answer:

The final size is approximately equal to the initial size due to a very small relative increase of 1.055\times 10^{- 7} in its size

Solution:

As per the question:

The energy of the proton beam, E = 250 GeV =250\times 10^{9}\times 1.6\times 10^{- 19} = 4\times 10^{- 8} J

Distance covered by photon, d = 1 km = 1000 m

Mass of proton, m_{p} = 1.67\times 10^{- 27} kg

The initial size of the wave packet, \Delta t_{o} = 1 mm = 1\times 10^{- 3} m

Now,

This is relativistic in nature

The rest mass energy associated with the proton is given by:

E = m_{p}c^{2}

E = 1.67\times 10^{- 27}\times (3\times 10^{8})^{2} = 1.503\times 10^{- 10} J

This energy of proton is \simeq 250 GeV

Thus the speed of the proton, v\simeq c

Now, the time taken to cover 1 km = 1000 m of the distance:

T = \frac{1000}{v}

T = \frac{1000}{c} = \frac{1000}{3\times 10^{8}} = 3.34\times 10^{- 6} s

Now, in accordance to the dispersion factor;

\frac{\delta t_{o}}{\Delta t_{o}} = \frac{ht_{o}}{2\pi m_{p}\Delta t_{o}^{2}}

\frac{\delta t_{o}}{\Delta t_{o}} = \frac{6.626\times 10^{- 34}\times 3.34\times 10^{- 6}}{2\pi 1.67\times 10^{- 27}\times (10^{- 3})^{2} = 1.055\times 10^{- 7}

Thus the increase in wave packet's width is relatively quite small.

Hence, we can say that:

\Delta t_{o} = \Delta t

where

\Delta t = final width

3 0
2 years ago
Human muscles have an efficiency of about __________. A. 9 to 17% B. 18 to 26% C. 27 to 35% D. 36 to 44%
xxTIMURxx [149]

Answer:

The correct answer would be B. 18 to 26%.

The muscle efficiency is calculated by dividing mechanical work output by total metabolic cost.

It is estimated that human muscles have an efficiency of about 18% to 26%.

The efficiency is low because most of the energy is lost when food energy is converted into ATP (adenosine triphophate).

In addition, there is second energy loss when energy in the form of ATP is converted into the mechanical energy such as rowing, cycling et cetera.

3 0
2 years ago
Read 2 more answers
Steam at 0.6 MPa, 200 oC, enters an insulated nozzle with a velocity of 50 m/s. It leaves at a pressure of 0.15 MPa and a veloci
Rudiy27

Answer:

x2 = 0.99

Explanation:

from superheated water table

at pressure p1 = 0.6MPa and temperature 200 degree celcius

h1 = 2850.6 kJ/kg

From energy equation we have following relation

\dot m( h1+\frac{v1^2}{2}+ gz1 )+ Q = \dot m( h2+\frac{v2^2}{2}+ gz1) + W

\dot m( h1+\frac{v1^2}{2}) = \dot m( h2+\frac{v2^2}{2})

h1+\frac{v1^2}{2} = h2+\frac{v2^2}{2}

2850.6 + [\frac{50^2}{2} * \frac{1 kJ/kg}{1000 m^2/S^2}] = h2 +[ \frac{600^2}{2} * \frac{1 kJ/kg}{1000 m^2/S^2}]

h2 = 2671.85 kJ/kg

from superheated water table

at pressure p2 = 0.15MPa

specific enthalpy of fluid hf = 467.13 kJ/kg

enthalpy change hfg = 2226.0 kJ/kg

specific enthalpy of the saturated gas hg = 2693.1 kJ/kg

as it can be seen from above value hf>h2>hg, so phase 2 is two phase region. so we have

quality of steam x2

h2 = hf + x2(hfg)

2671.85 = 467.13 +x2*2226.0

x2 = 0.99

6 0
2 years ago
Two cyclists start on a race between points A and D on two different routes. Cyclist X takes the route passing through the equid
ollegr [7]
The displacement is the shortest distance between two points, which is 546.41. The displacement for both is 546.41 meters

Average velocity of X = (200 + 200 + 200) / 30
Average velocity of X = 20 m/s

Average velocity of Y = 546.41 / 30 = 18.2 m/s
8 0
2 years ago
Read 2 more answers
|| Climbing ropes stretch when they catch a falling climber, thus increasing the time it takes the climber to come to rest and r
Otrada [13]

To solve this problem it is necessary to apply the concepts related to Newton's second law and the kinematic equations of movement description.

Newton's second law is defined as

F = ma

Where,

m = mass

a = acceleration

From this equation we can figure the acceleration out, then

a = \frac{F}{m}

a = \frac{11*10^3}{80}

a = 137.5m/s

From the cinematic equations of motion we know that

v_f^2-v_i^2 = 2ax

Where,

v_f =Final velocity

v_i =Initial velocity

a = acceleration

x = displacement

There is not Final velocity and the acceleration is equal to the gravity, then

v_f^2-v_i^2 = 2ax

0-v_i^2 = 2(-g)x

v_i =\sqrt{2gx}

v_i = \sqrt{2*9.8*4.8}

v_i = 9.69m/s

From the equation of motion where acceleration is equal to the velocity in function of time we have

a = \frac{v_i}{t}

t = \frac{v_i}{a}

t =\frac{9.69}{137.5}

t = 0.0705s

Therefore the time required is 0.0705s

4 0
2 years ago
Read 2 more answers
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